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Solution
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Q.1 Correct
Q.1 In-correct
Q.1 Unattempt

An electron in the hydrogen atom initially in the fourth excited state makes a transition to $\mathrm{n}^{\text {th }}$ energy state by emitting a photon of energy 2.86 eV . The integer value of n will be__________.

JEE Main 2025 (Online) 3rd April Evening Shift

An electron in the hydrogen atom initially in the fourth excited state makes a transition to $\mathrm{n}^{\text {th }}$ energy state by emitting a photon of energy 2.86 eV . The integer value of n will be__________.

JEE Main 2025 (Online) 3rd April Evening Shift
Q.2 Correct
Q.2 In-correct
Q.2 Unattempt

A radioactive nucleus $\mathrm{n}_2$ has 3 times the decay constant as compared to the decay constant of another radioactive nucleus $n_1$. If initial number of both nuclei are the same, what is the ratio of number of nuclei of $n_2$ to the number of nuclei of $n_1$, after one half-life of $n_1$ ?



JEE Main 2025 (Online) 23rd January Morning Shift

A radioactive nucleus $\mathrm{n}_2$ has 3 times the decay constant as compared to the decay constant of another radioactive nucleus $n_1$. If initial number of both nuclei are the same, what is the ratio of number of nuclei of $n_2$ to the number of nuclei of $n_1$, after one half-life of $n_1$ ?



JEE Main 2025 (Online) 23rd January Morning Shift
Q.3 Correct
Q.3 In-correct
Q.3 Unattempt

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : The binding energy per nucleon is found to be practically independent of the atomic number A , for nuclei with mass numbers between 30 and 170 .

Reason (R) : Nuclear force is long range.In the light of the above statements, choose the correct answer from the options given below :



JEE Main 2025 (Online) 23rd January Evening Shift

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : The binding energy per nucleon is found to be practically independent of the atomic number A , for nuclei with mass numbers between 30 and 170 .

Reason (R) : Nuclear force is long range.In the light of the above statements, choose the correct answer from the options given below :



JEE Main 2025 (Online) 23rd January Evening Shift
Q.4 Correct
Q.4 In-correct
Q.4 Unattempt
During the transition of electron from state A to state C of a Bohr atom, the wavelength of emitted radiation is $2000 \mathop A\limits^o$ and it becomes $6000 \mathop A\limits^o$ when the electron jumps from state B to state C. Then the wavelength of the radiation emitted during the transition of electrons from state A to state B is

JEE Main 2025 (Online) 24th January Morning Shift
During the transition of electron from state A to state C of a Bohr atom, the wavelength of emitted radiation is $2000 \mathop A\limits^o$ and it becomes $6000 \mathop A\limits^o$ when the electron jumps from state B to state C. Then the wavelength of the radiation emitted during the transition of electrons from state A to state B is

JEE Main 2025 (Online) 24th January Morning Shift
Q.5 Correct
Q.5 In-correct
Q.5 Unattempt

The energy E and momentum p of a moving body of mass m are related by some equation. Given that c represents the speed of light, identify the correct equation



JEE Main 2025 (Online) 24th January Evening Shift

The energy E and momentum p of a moving body of mass m are related by some equation. Given that c represents the speed of light, identify the correct equation



JEE Main 2025 (Online) 24th January Evening Shift
Q.6 Correct
Q.6 In-correct
Q.6 Unattempt

Choose the correct nuclear process from the below options [ p : proton, n : neutron, $\mathrm{e}^{-}$: electron, $\mathrm{e}^{+}$: positron, $v:$ neutrino, $\bar{v}:$ antineutrino]



JEE Main 2025 (Online) 28th January Morning Shift

Choose the correct nuclear process from the below options [ p : proton, n : neutron, $\mathrm{e}^{-}$: electron, $\mathrm{e}^{+}$: positron, $v:$ neutrino, $\bar{v}:$ antineutrino]



JEE Main 2025 (Online) 28th January Morning Shift
Q.7 Correct
Q.7 In-correct
Q.7 Unattempt

The frequency of revolution of the electron in Bohr's orbit varies with n, the principal quantum number as:



JEE Main 2025 (Online) 28th January Evening Shift

The frequency of revolution of the electron in Bohr's orbit varies with n, the principal quantum number as:



JEE Main 2025 (Online) 28th January Evening Shift
Q.8 Correct
Q.8 In-correct
Q.8 Unattempt

The number of spectral lines emitted by atomic hydrogen that is in the 4th energy level, is



JEE Main 2025 (Online) 29th January Evening Shift

The number of spectral lines emitted by atomic hydrogen that is in the 4th energy level, is



JEE Main 2025 (Online) 29th January Evening Shift
Q.9 Correct
Q.9 In-correct
Q.9 Unattempt

Considering Bohr's atomic model for hydrogen atom :

(A) the energy of H atom in ground state is same as energy of $\mathrm{He}^{+}$ion in its first excited state.

(B) the energy of H atom in ground state is same as that for $\mathrm{Li}^{++}$ ion in its second excited state.

(C) the energy of H atom in its ground state is same as that of $\mathrm{He}^{+}$ion for its ground state.

(D) the energy of $\mathrm{He}^{+}$ion in its first excited state is same as that for $\mathrm{Li}^{++}$ion in its ground state.

Choose the correct answer from the options given below :



JEE Main 2025 (Online) 2nd April Morning Shift

Considering Bohr's atomic model for hydrogen atom :

(A) the energy of H atom in ground state is same as energy of $\mathrm{He}^{+}$ion in its first excited state.

(B) the energy of H atom in ground state is same as that for $\mathrm{Li}^{++}$ ion in its second excited state.

(C) the energy of H atom in its ground state is same as that of $\mathrm{He}^{+}$ion for its ground state.

(D) the energy of $\mathrm{He}^{+}$ion in its first excited state is same as that for $\mathrm{Li}^{++}$ion in its ground state.

Choose the correct answer from the options given below :



JEE Main 2025 (Online) 2nd April Morning Shift
Q.10 Correct
Q.10 In-correct
Q.10 Unattempt
Assuming the validity of Bohr's atomic model for hydrogen like ions the radius of $\mathrm{Li}^{++}$ ion in its ground state is given by $\frac{1}{X} a_0$, where $X=$ __________ (Where $\mathrm{a}_0$ is the first Bohr's radius.)

JEE Main 2025 (Online) 2nd April Evening Shift
Assuming the validity of Bohr's atomic model for hydrogen like ions the radius of $\mathrm{Li}^{++}$ ion in its ground state is given by $\frac{1}{X} a_0$, where $X=$ __________ (Where $\mathrm{a}_0$ is the first Bohr's radius.)

JEE Main 2025 (Online) 2nd April Evening Shift
Q.11 Correct
Q.11 In-correct
Q.11 Unattempt
Energy released when two deuterons $\left({ }_1 \mathrm{H}^2\right)$ fuse to form a helium nucleus $\left({ }_2 \mathrm{He}^4\right)$ is :(Given : Binding energy per nucleon of ${ }_1 \mathrm{H}^2=1.1 \mathrm{MeV}$ and binding energy per nucleon of ${ }_2 \mathrm{He}^4=7.0 \mathrm{MeV}$ )

JEE Main 2025 (Online) 2nd April Evening Shift
Energy released when two deuterons $\left({ }_1 \mathrm{H}^2\right)$ fuse to form a helium nucleus $\left({ }_2 \mathrm{He}^4\right)$ is :(Given : Binding energy per nucleon of ${ }_1 \mathrm{H}^2=1.1 \mathrm{MeV}$ and binding energy per nucleon of ${ }_2 \mathrm{He}^4=7.0 \mathrm{MeV}$ )

JEE Main 2025 (Online) 2nd April Evening Shift
Q.12 Correct
Q.12 In-correct
Q.12 Unattempt

$$ \text { Match the LIST-I with LIST-II } $$

List - I
 List - II
A. $$
{ }_0^1 \mathrm{n}+{ }_{92}^{235} \mathrm{U} \rightarrow{ }_{54}^{140} \mathrm{Xe}+{ }_{38}^{94} \mathrm{Sr}+2{ }_0^1 \mathrm{n}
$$
 I. $$
\text { Chemical reaction }
$$
B. $$
2 \mathrm{H}_2+\mathrm{O}_2 \rightarrow 2 \mathrm{H}_2 \mathrm{O}
$$
 II. $$
\text { Fusion with +ve } \mathrm{Q} \text { value }
$$
C. $$
{ }_1^2 \mathrm{H}+{ }_1^2 \mathrm{H} \rightarrow{ }_2^3 \mathrm{He}+{ }_0^1 \mathrm{n}
$$
 III. $$
\text { Fission }
$$
D. $$
{ }_1^1 \mathrm{H}+{ }_1^3 \mathrm{H} \rightarrow{ }_1^2 \mathrm{H}+{ }_1^2 \mathrm{H}
$$
 IV. $$
\text { Fusion with -ve } Q \text { value }
$$
$$\text { Choose the correct answer from the options given below: }$$

JEE Main 2025 (Online) 3rd April Morning Shift

$$ \text { Match the LIST-I with LIST-II } $$

List - I
 List - II
A. $$
{ }_0^1 \mathrm{n}+{ }_{92}^{235} \mathrm{U} \rightarrow{ }_{54}^{140} \mathrm{Xe}+{ }_{38}^{94} \mathrm{Sr}+2{ }_0^1 \mathrm{n}
$$
 I. $$
\text { Chemical reaction }
$$
B. $$
2 \mathrm{H}_2+\mathrm{O}_2 \rightarrow 2 \mathrm{H}_2 \mathrm{O}
$$
 II. $$
\text { Fusion with +ve } \mathrm{Q} \text { value }
$$
C. $$
{ }_1^2 \mathrm{H}+{ }_1^2 \mathrm{H} \rightarrow{ }_2^3 \mathrm{He}+{ }_0^1 \mathrm{n}
$$
 III. $$
\text { Fission }
$$
D. $$
{ }_1^1 \mathrm{H}+{ }_1^3 \mathrm{H} \rightarrow{ }_1^2 \mathrm{H}+{ }_1^2 \mathrm{H}
$$
 IV. $$
\text { Fusion with -ve } Q \text { value }
$$
$$\text { Choose the correct answer from the options given below: }$$

JEE Main 2025 (Online) 3rd April Morning Shift
Q.13 Correct
Q.13 In-correct
Q.13 Unattempt

Given below are two statements: one is labelled as $\mathbf{A s s e r t i o n} \mathbf{A}$ and the other is labelled as Reason $\mathbf{R}$

Assertion A : The Bohr model is applicable to hydrogen and hydrogen-like atoms only.

Reason $\mathbf{R}$ : The formulation of Bohr model does not include repulsive force between electrons.

In the light of the above statements, choose the correct answer from the options given below



JEE Main 2025 (Online) 3rd April Evening Shift

Given below are two statements: one is labelled as $\mathbf{A s s e r t i o n} \mathbf{A}$ and the other is labelled as Reason $\mathbf{R}$

Assertion A : The Bohr model is applicable to hydrogen and hydrogen-like atoms only.

Reason $\mathbf{R}$ : The formulation of Bohr model does not include repulsive force between electrons.

In the light of the above statements, choose the correct answer from the options given below



JEE Main 2025 (Online) 3rd April Evening Shift
Q.14 Correct
Q.14 In-correct
Q.14 Unattempt

Considering the Bohr model of hydrogen like atoms, the ratio of the radius of $5^{\text {th }}$ orbit of the electron in $\mathrm{Li}^{2+}$ and $\mathrm{He}^{+}$is



JEE Main 2025 (Online) 4th April Morning Shift

Considering the Bohr model of hydrogen like atoms, the ratio of the radius of $5^{\text {th }}$ orbit of the electron in $\mathrm{Li}^{2+}$ and $\mathrm{He}^{+}$is



JEE Main 2025 (Online) 4th April Morning Shift
Q.15 Correct
Q.15 In-correct
Q.15 Unattempt

Given below are two statements :

Statement (I) : The dimensions of Planck's constant and angular momentum are same.

Statement (II) : In Bohr's model electron revolve around the nucleus only in those orbits for which angular momentum is integral multiple of Planck's constant.

In the light of the above statements, choose the most appropriate answer from the options given below :



JEE Main 2025 (Online) 4th April Evening Shift

Given below are two statements :

Statement (I) : The dimensions of Planck's constant and angular momentum are same.

Statement (II) : In Bohr's model electron revolve around the nucleus only in those orbits for which angular momentum is integral multiple of Planck's constant.

In the light of the above statements, choose the most appropriate answer from the options given below :



JEE Main 2025 (Online) 4th April Evening Shift
Q.16 Correct
Q.16 In-correct
Q.16 Unattempt

A radioactive material $P$ first decays into $Q$ and then $Q$ decays to non-radioactive material $R$. Which of the following figure represents time dependent mass of $P, Q$ and $R$ ?



JEE Main 2025 (Online) 4th April Evening Shift

A radioactive material $P$ first decays into $Q$ and then $Q$ decays to non-radioactive material $R$. Which of the following figure represents time dependent mass of $P, Q$ and $R$ ?



JEE Main 2025 (Online) 4th April Evening Shift
Q.17 Correct
Q.17 In-correct
Q.17 Unattempt

For a hydrogen atom, the ratio of the largest wavelength of Lyman series to that of the Balmer series is



JEE Main 2025 (Online) 7th April Morning Shift

For a hydrogen atom, the ratio of the largest wavelength of Lyman series to that of the Balmer series is



JEE Main 2025 (Online) 7th April Morning Shift
Q.18 Correct
Q.18 In-correct
Q.18 Unattempt

In a hydrogen like ion, the energy difference between the $2^{\text {nd }}$ excitation energy state and ground is 108.8 eV . The atomic number of the ion is:



JEE Main 2025 (Online) 7th April Morning Shift

In a hydrogen like ion, the energy difference between the $2^{\text {nd }}$ excitation energy state and ground is 108.8 eV . The atomic number of the ion is:



JEE Main 2025 (Online) 7th April Morning Shift
Q.19 Correct
Q.19 In-correct
Q.19 Unattempt

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): The density of the copper $(^ {64}_{29} \text{Cu})$ nucleus is greater than that of the carbon $(^ {12}_{6} \text{C})$ nucleus.

Reason (R): The nucleus of mass number A has a radius proportional to $ A^{1/3} $.

In the light of the above statements, choose the most appropriate answer from the options given below:



JEE Main 2025 (Online) 7th April Evening Shift

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): The density of the copper $(^ {64}_{29} \text{Cu})$ nucleus is greater than that of the carbon $(^ {12}_{6} \text{C})$ nucleus.

Reason (R): The nucleus of mass number A has a radius proportional to $ A^{1/3} $.

In the light of the above statements, choose the most appropriate answer from the options given below:



JEE Main 2025 (Online) 7th April Evening Shift
Q.20 Correct
Q.20 In-correct
Q.20 Unattempt

For a nucleus of mass number A and radius R, the mass density of nucleus can be represented as



JEE Main 2025 (Online) 8th April Evening Shift

For a nucleus of mass number A and radius R, the mass density of nucleus can be represented as



JEE Main 2025 (Online) 8th April Evening Shift
Q.21 Correct
Q.21 In-correct
Q.21 Unattempt
The radius of third stationary orbit of electron for Bohr's atom is R. The radius of fourth stationary orbit will be:
[27-Jan-2024 Shift 1]
The radius of third stationary orbit of electron for Bohr's atom is R. The radius of fourth stationary orbit will be:
[27-Jan-2024 Shift 1]
Q.22 Correct
Q.22 In-correct
Q.22 Unattempt
If Rydberg's constant is R, the longest wavelength of radiation in Paschen series will be ‌
α
7R
, where α=____
[27-Jan-2024 Shift 2]
If Rydberg's constant is R, the longest wavelength of radiation in Paschen series will be ‌
α
7R
, where α=____
[27-Jan-2024 Shift 2]
Q.23 Correct
Q.23 In-correct
Q.23 Unattempt
When a hydrogen atom going from n=2 to n=1 emits a photon, its recoil speed is ‌
X
5
m∕ s. Where x=____ (Use : mass of hydrogen atom =1.6×10−27‌kg)
[29-Jan-2024 Shift 1]
When a hydrogen atom going from n=2 to n=1 emits a photon, its recoil speed is ‌
X
5
m∕ s. Where x=____ (Use : mass of hydrogen atom =1.6×10−27‌kg)
[29-Jan-2024 Shift 1]
Q.24 Correct
Q.24 In-correct
Q.24 Unattempt
Given below are two statements:
Statement I: Fluorine has most negative electron gain enthalpy in its group.
Statement II: Oxygen has least negative electron gain enthalpy in its group.
In the light of the above statements, choose the most appropriate from the options given below.
[29-Jan-2024 Shift 2]
Given below are two statements:
Statement I: Fluorine has most negative electron gain enthalpy in its group.
Statement II: Oxygen has least negative electron gain enthalpy in its group.
In the light of the above statements, choose the most appropriate from the options given below.
[29-Jan-2024 Shift 2]
Q.25 Correct
Q.25 In-correct
Q.25 Unattempt
Hydrogen atom is bombarded with electrons accelerated through a potential different of V, which causes excitation of hydrogen atoms. If the experiment is being formed at T=0K. The minimum potential difference needed to observe any Balmer series lines in the emission spectra will be ‌
α
10
V, where α=___
[29-Jan-2024 Shift 2]
Hydrogen atom is bombarded with electrons accelerated through a potential different of V, which causes excitation of hydrogen atoms. If the experiment is being formed at T=0K. The minimum potential difference needed to observe any Balmer series lines in the emission spectra will be ‌
α
10
V, where α=___
[29-Jan-2024 Shift 2]
Q.26 Correct
Q.26 In-correct
Q.26 Unattempt
The ratio of the magnitude of the kinetic energy to the potential energy of an electron in the 5‌th ‌ excited state of a hydrogen atom is :
[30-Jan-2024 Shift 1]
The ratio of the magnitude of the kinetic energy to the potential energy of an electron in the 5‌th ‌ excited state of a hydrogen atom is :
[30-Jan-2024 Shift 1]
Q.27 Correct
Q.27 In-correct
Q.27 Unattempt
The ratio of the magnitude of the kinetic energy to the potential energy of an electron in the 5‌th ‌ excited state of a hydrogen atom is :
[30-Jan-2024 Shift 1]
The ratio of the magnitude of the kinetic energy to the potential energy of an electron in the 5‌th ‌ excited state of a hydrogen atom is :
[30-Jan-2024 Shift 1]
Q.28 Correct
Q.28 In-correct
Q.28 Unattempt
A electron of hydrogen atom on an excited state is having energy En=−0.85‌eV. The maximum number of allowed transitions to lower energy level is ..... . .
[30-Jan-2024 Shift 1]
A electron of hydrogen atom on an excited state is having energy En=−0.85‌eV. The maximum number of allowed transitions to lower energy level is ..... . .
[30-Jan-2024 Shift 1]
Q.29 Correct
Q.29 In-correct
Q.29 Unattempt
An electron revolving in n‌th ‌ Bohr orbit has magnetic moment µn. If µnαnx, the value of x is:
[30-Jan-2024 Shift 2]
An electron revolving in n‌th ‌ Bohr orbit has magnetic moment µn. If µnαnx, the value of x is:
[30-Jan-2024 Shift 2]
Q.30 Correct
Q.30 In-correct
Q.30 Unattempt
The mass defect in a particular reaction is 0.4g. The amount of energy liberated is n×107‌kWh, where n=_______(speed of light =3×108m∕ s)
[31-Jan-2024 Shift 1]
The mass defect in a particular reaction is 0.4g. The amount of energy liberated is n×107‌kWh, where n=_______(speed of light =3×108m∕ s)
[31-Jan-2024 Shift 1]
Q.31 Correct
Q.31 In-correct
Q.31 Unattempt
In a nuclear fission process, a high mass nuclide (A≈236) with binding energy 7.6 MeV/Nucleon dissociated into middle mass nuclides (A≈118), having binding energy of 8.6‌MeV∕Nucleon. The energy released in the process would be_____ MeV.
[27-Jan-2024 Shift 1]
In a nuclear fission process, a high mass nuclide (A≈236) with binding energy 7.6 MeV/Nucleon dissociated into middle mass nuclides (A≈118), having binding energy of 8.6‌MeV∕Nucleon. The energy released in the process would be_____ MeV.
[27-Jan-2024 Shift 1]
Q.32 Correct
Q.32 In-correct
Q.32 Unattempt
The atomic mass of ‌6C12 is 12.000000u and that of ‌6C13 is 13.003354u. The required energy to remove a neutron from ‌6C13, if mass of neutron is 1.008665u, will be :
[27-Jan-2024 Shift 2]
The atomic mass of ‌6C12 is 12.000000u and that of ‌6C13 is 13.003354u. The required energy to remove a neutron from ‌6C13, if mass of neutron is 1.008665u, will be :
[27-Jan-2024 Shift 2]
Q.33 Correct
Q.33 In-correct
Q.33 Unattempt
The explosive in a Hydrogen bomb is a mixture of ‌1H2,‌1H3 and ‌3Li6 in some condensed form. The chain reaction is given by
‌3Li6+‌0n1→‌2He4+‌1H3
‌1H2+‌1H3→‌2He4+‌0n1
During the explosion the energy released is approximately
[Given : M(Li)=6.01690‌amu.M(‌1H2)=2.01471 amu. M(‌2He4)=4.00388‌amu, and 1‌amu=931.5 MeV]
[29-Jan-2024 Shift 1]
The explosive in a Hydrogen bomb is a mixture of ‌1H2,‌1H3 and ‌3Li6 in some condensed form. The chain reaction is given by
‌3Li6+‌0n1→‌2He4+‌1H3
‌1H2+‌1H3→‌2He4+‌0n1
During the explosion the energy released is approximately
[Given : M(Li)=6.01690‌amu.M(‌1H2)=2.01471 amu. M(‌2He4)=4.00388‌amu, and 1‌amu=931.5 MeV]
[29-Jan-2024 Shift 1]
Q.34 Correct
Q.34 In-correct
Q.34 Unattempt
In a nuclear fission reaction of an isotope of mass M, three similar daughter nuclei of same mass are formed. The speed of a daughter nuclei in terms of mass defect ∆M will be :
[30-Jan-2024 Shift 2]
In a nuclear fission reaction of an isotope of mass M, three similar daughter nuclei of same mass are formed. The speed of a daughter nuclei in terms of mass defect ∆M will be :
[30-Jan-2024 Shift 2]
Q.35 Correct
Q.35 In-correct
Q.35 Unattempt
The mass number of nucleus having radius equal to half of the radius of nucleus with mass number 192 is:
[31-Jan-2024 Shift 2]
The mass number of nucleus having radius equal to half of the radius of nucleus with mass number 192 is:
[31-Jan-2024 Shift 2]
Q.36 Correct
Q.36 In-correct
Q.36 Unattempt
A nucleus has mass number A1 and volume V1. Another nucleus has mass number A2 and volume V2. If relation between mass number is A2=4A1, then ‌
V2
V1
=____
[31-Jan-2024 Shift 2]
A nucleus has mass number A1 and volume V1. Another nucleus has mass number A2 and volume V2. If relation between mass number is A2=4A1, then ‌
V2
V1
=____
[31-Jan-2024 Shift 2]
Q.37 Correct
Q.37 In-correct
Q.37 Unattempt
The minimum energy required by a hydrogen atom in ground state to emit radiation in Balmer series is nearly :
[1-Feb-2024 Shift 1]
The minimum energy required by a hydrogen atom in ground state to emit radiation in Balmer series is nearly :
[1-Feb-2024 Shift 1]
Q.38 Correct
Q.38 In-correct
Q.38 Unattempt
A particular hydrogen - like ion emits the radiation of frequency 3×1015‌Hz when it makes transition from n=2 to n=1. The frequency of radiation emitted in transition from n=3 to n=1 is ‌
x
9
×1015‌Hz, when x=_____
[1-Feb-2024 Shift 2]
A particular hydrogen - like ion emits the radiation of frequency 3×1015‌Hz when it makes transition from n=2 to n=1. The frequency of radiation emitted in transition from n=3 to n=1 is ‌
x
9
×1015‌Hz, when x=_____
[1-Feb-2024 Shift 2]
Q.39 Correct
Q.39 In-correct
Q.39 Unattempt
The radius of a nucleus of mass number 64 is 4.8 fermi. Then the mass number of another nucleus having radius of 4 fermi is ‌
1000
x
, where x is_____
[1-Feb-2024 Shift 1]
The radius of a nucleus of mass number 64 is 4.8 fermi. Then the mass number of another nucleus having radius of 4 fermi is ‌
1000
x
, where x is_____
[1-Feb-2024 Shift 1]
Q.40 Correct
Q.40 In-correct
Q.40 Unattempt
From the statements given below :
(A) The angular momentum of an electron in n‌th ‌ orbit is an integral multiple of h.
(B) Nuclear forces do not obey inverse square law.
(C) Nuclear forces are spin dependent.
(D) Nuclear forces are central and charge independent.
(E) Stability of nucleus is inversely proportional to the value of packing fraction.
Choose the correct answer from the options given below :
[1-Feb-2024 Shift 2]
From the statements given below :
(A) The angular momentum of an electron in n‌th ‌ orbit is an integral multiple of h.
(B) Nuclear forces do not obey inverse square law.
(C) Nuclear forces are spin dependent.
(D) Nuclear forces are central and charge independent.
(E) Stability of nucleus is inversely proportional to the value of packing fraction.
Choose the correct answer from the options given below :
[1-Feb-2024 Shift 2]
Q.41 Correct
Q.41 In-correct
Q.41 Unattempt
If the binding energy of ground state electron in a hydrogen atom is 13.6‌eV, then, the energy required to remove the electron from the second excited state of Li2+ will be: x×10−1‌eV. The value of x is _______ .
[31-Jan-2023 Shift 2]
If the binding energy of ground state electron in a hydrogen atom is 13.6‌eV, then, the energy required to remove the electron from the second excited state of Li2+ will be: x×10−1‌eV. The value of x is _______ .
[31-Jan-2023 Shift 2]
Q.42 Correct
Q.42 In-correct
Q.42 Unattempt
Consider the following radioactive decay process
218
‌
84
A‌
α
⟶
A1
β−
⟶
A2‌
γ
⟶
A3‌
α
⟶
A4
β+
⟶
A5‌
γ
⟶
A6 The mass number and the atomic number A6 are given by :
[24-Jan-2023 Shift 1]
Consider the following radioactive decay process
218
‌
84
A‌
α
⟶
A1
β−
⟶
A2‌
γ
⟶
A3‌
α
⟶
A4
β+
⟶
A5‌
γ
⟶
A6 The mass number and the atomic number A6 are given by :
[24-Jan-2023 Shift 1]
Q.43 Correct
Q.43 In-correct
Q.43 Unattempt
The energy released per fission of nucleus of ‌240X is 200‌MeV. The energy released if all the atoms in 120g of pure ‌240X undergo fission is ____×1025
MeV.
(. Given NA=6×1023)
[24-Jan-2023 Shift 2]
The energy released per fission of nucleus of ‌240X is 200‌MeV. The energy released if all the atoms in 120g of pure ‌240X undergo fission is ____×1025
MeV.
(. Given NA=6×1023)
[24-Jan-2023 Shift 2]
Q.44 Correct
Q.44 In-correct
Q.44 Unattempt
The ratio of the density of oxygen nucleus (‌816O) and helium nucleus (‌24‌He) is
[25-Jan-2023 Shift 1]
The ratio of the density of oxygen nucleus (‌816O) and helium nucleus (‌24‌He) is
[25-Jan-2023 Shift 1]
Q.45 Correct
Q.45 In-correct
Q.45 Unattempt
If a radioactive element having half-life of 30‌min is undergoing beta decay, the fraction of radioactive element remains undecayed after 90‌min. will be :
[29-Jan-2023 Shift 1]
If a radioactive element having half-life of 30‌min is undergoing beta decay, the fraction of radioactive element remains undecayed after 90‌min. will be :
[29-Jan-2023 Shift 1]
Q.46 Correct
Q.46 In-correct
Q.46 Unattempt
A radioactive element
242
‌
92
X emits two α-particles, one electron and two positrons. The product nucleus is represented by
234
‌
p
Y. The value of P is _______
[29-Jan-2023 Shift 1]
A radioactive element
242
‌
92
X emits two α-particles, one electron and two positrons. The product nucleus is represented by
234
‌
p
Y. The value of P is _______
[29-Jan-2023 Shift 1]
Q.47 Correct
Q.47 In-correct
Q.47 Unattempt
Substance A has atomic mass number 16 and half life of 1 day. Another substance B has atomic mass number 32 and half life of ‌
1
2
 day. If both A and B simultaneously start undergo radio activity at the same time with initial mass 320g each, how many total atoms of A and B combined would be left after 2 days.
[29-Jan-2023 Shift 2]
Substance A has atomic mass number 16 and half life of 1 day. Another substance B has atomic mass number 32 and half life of ‌
1
2
 day. If both A and B simultaneously start undergo radio activity at the same time with initial mass 320g each, how many total atoms of A and B combined would be left after 2 days.
[29-Jan-2023 Shift 2]
Q.48 Correct
Q.48 In-correct
Q.48 Unattempt
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : The nuclear density of nuclides ‌510B,‌36‌Li,‌2656‌Fe,‌1020‌Ne and ‌83209‌Bi can be arranged as ρBiN>ρFeN>ρNeN>ρBN>ρLiN.
Reason R : The radius R of nucleus is related to its mass number A as R=R0A1∕3, where R0 is a constant.
In the light of the above statement, choose the correct answer from the options given below :
[30-Jan-2023 Shift 2]
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : The nuclear density of nuclides ‌510B,‌36‌Li,‌2656‌Fe,‌1020‌Ne and ‌83209‌Bi can be arranged as ρBiN>ρFeN>ρNeN>ρBN>ρLiN.
Reason R : The radius R of nucleus is related to its mass number A as R=R0A1∕3, where R0 is a constant.
In the light of the above statement, choose the correct answer from the options given below :
[30-Jan-2023 Shift 2]
Q.49 Correct
Q.49 In-correct
Q.49 Unattempt
A radioactive nucleus decays by two different process. The half life of the first process is 5 minutes and that of the second process is 30 s. The effective half-life of the nucleus is calculated to be ‌
α
11
 s. The value of α is _______.
[30-Jan-2023 Shift 2]
A radioactive nucleus decays by two different process. The half life of the first process is 5 minutes and that of the second process is 30 s. The effective half-life of the nucleus is calculated to be ‌
α
11
 s. The value of α is _______.
[30-Jan-2023 Shift 2]
Q.50 Correct
Q.50 In-correct
Q.50 Unattempt
A free neutron decays into a proton but a free proton does not decay into neutron. This is because
[31-Jan-2023 Shift 1]
A free neutron decays into a proton but a free proton does not decay into neutron. This is because
[31-Jan-2023 Shift 1]
Q.51 Correct
Q.51 In-correct
Q.51 Unattempt
The energy levels of an atom is shown is figure. Which one of these transitions will result in the emission of a photon of wavelength 124.1‌nm ? Given (h=6.62×10−34‌Js)

[25-Jan-2023 Shift 2]
The energy levels of an atom is shown is figure. Which one of these transitions will result in the emission of a photon of wavelength 124.1‌nm ? Given (h=6.62×10−34‌Js)

[25-Jan-2023 Shift 2]
Q.52 Correct
Q.52 In-correct
Q.52 Unattempt
Speed of an electron in Bohr's 7‌th ‌ orbit for Hydrogen atom is 3.6×106m∕ s. The corresponding speed of the electron in 3‌rd ‌ orbit, in m∕ s is :
[30-Jan-2023 Shift 1]
Speed of an electron in Bohr's 7‌th ‌ orbit for Hydrogen atom is 3.6×106m∕ s. The corresponding speed of the electron in 3‌rd ‌ orbit, in m∕ s is :
[30-Jan-2023 Shift 1]
Q.53 Correct
Q.53 In-correct
Q.53 Unattempt
For hydrogen atom, λ1 and λ2 are the wavelengths corresponding to the transitions 1 and 2 respectively as shown in figure. The ratio of λ1 and λ2 is ‌
x
32
. The value of x is _______.

[31-Jan-2023 Shift 1]
For hydrogen atom, λ1 and λ2 are the wavelengths corresponding to the transitions 1 and 2 respectively as shown in figure. The ratio of λ1 and λ2 is ‌
x
32
. The value of x is _______.

[31-Jan-2023 Shift 1]
Q.54 Correct
Q.54 In-correct
Q.54 Unattempt
The radius of electron's second stationary orbit in Bohr's atom is R. The radius of 3 rd orbit will be
[31-Jan-2023 Shift 2]
The radius of electron's second stationary orbit in Bohr's atom is R. The radius of 3 rd orbit will be
[31-Jan-2023 Shift 2]
Q.55 Correct
Q.55 In-correct
Q.55 Unattempt
Assume that protons and neutrons have equal masses. Mass of a nucleon is 1.6×10−27‌kg and radius of nucleus is 1.5×10−15A1∕3m. The approximate ratio of the nuclear density and water density is n×1013. The value of n is____
[24-Jan-2023 Shift 1]
Assume that protons and neutrons have equal masses. Mass of a nucleon is 1.6×10−27‌kg and radius of nucleus is 1.5×10−15A1∕3m. The approximate ratio of the nuclear density and water density is n×1013. The value of n is____
[24-Jan-2023 Shift 1]
Q.56 Correct
Q.56 In-correct
Q.56 Unattempt
A photon is emitted in transition from n=4 to n=1 level in hydrogen atom. The corresponding wavelength for this transition is
(given, h=4×10−15‌eVs ) :
[24-Jan-2023 Shift 2]
A photon is emitted in transition from n=4 to n=1 level in hydrogen atom. The corresponding wavelength for this transition is
(given, h=4×10−15‌eVs ) :
[24-Jan-2023 Shift 2]
Q.57 Correct
Q.57 In-correct
Q.57 Unattempt
The wavelength of the radiation emitted is λ0 when an electron jumps from the second excited state to the first excited state of hydrogen atom. If the electron jumps from the third excited state to the second orbit of the hydrogen atom, the wavelength of the radiation emitted will be ‌20∕xλ0. The value of x is _______.
[25-Jan-2023 Shift 1]
The wavelength of the radiation emitted is λ0 when an electron jumps from the second excited state to the first excited state of hydrogen atom. If the electron jumps from the third excited state to the second orbit of the hydrogen atom, the wavelength of the radiation emitted will be ‌20∕xλ0. The value of x is _______.
[25-Jan-2023 Shift 1]
Q.58 Correct
Q.58 In-correct
Q.58 Unattempt
The mass of proton, neutron and helium nucleus are respectively 1.0073u,1.0087u and 4.0015u. The binding energy of helium nucleus is:
[1-Feb-2023 Shift 1]
The mass of proton, neutron and helium nucleus are respectively 1.0073u,1.0087u and 4.0015u. The binding energy of helium nucleus is:
[1-Feb-2023 Shift 1]
Q.59 Correct
Q.59 In-correct
Q.59 Unattempt
A light of energy 12.75‌eV is incident on a hydrogen atom in its ground state. The atom absorbs the radiation and reaches to one of its excited states. The angular momentum of the atom in the excited state is ‌
x
π
×10−17‌eVs. The value of x is _______ (use h=4.14×10−15‌eVs,c=3×108 ms−1)
[1-Feb-2023 Shift 1]
A light of energy 12.75‌eV is incident on a hydrogen atom in its ground state. The atom absorbs the radiation and reaches to one of its excited states. The angular momentum of the atom in the excited state is ‌
x
π
×10−17‌eVs. The value of x is _______ (use h=4.14×10−15‌eVs,c=3×108 ms−1)
[1-Feb-2023 Shift 1]
Q.60 Correct
Q.60 In-correct
Q.60 Unattempt
An electron of a hydrogen like atom, having Z=4, jumps from 4‌th ‌ energy state to 2‌nd ‌ energy state, The energy released in this process, will be:
( Given Rch=13.6‌eV)
Where R= Rydberg constant
c= Speed of light in vacuum
h= Planck's constant
[1-Feb-2023 Shift 2]
An electron of a hydrogen like atom, having Z=4, jumps from 4‌th ‌ energy state to 2‌nd ‌ energy state, The energy released in this process, will be:
( Given Rch=13.6‌eV)
Where R= Rydberg constant
c= Speed of light in vacuum
h= Planck's constant
[1-Feb-2023 Shift 2]
Q.61 Correct
Q.61 In-correct
Q.61 Unattempt
Nucleus a having Z=17 and equal number of protons and neutrons has 1.2‌MeV binding energy per nucleon.
Another nucleus B of Z=12 has total 26 nucleons and 1.8‌MeV binding energy per nucleons.
The difference of binding energy of B and A will be _______ MeV.
[1-Feb-2023 Shift 2]
Nucleus a having Z=17 and equal number of protons and neutrons has 1.2‌MeV binding energy per nucleon.
Another nucleus B of Z=12 has total 26 nucleons and 1.8‌MeV binding energy per nucleons.
The difference of binding energy of B and A will be _______ MeV.
[1-Feb-2023 Shift 2]
Q.62 Correct
Q.62 In-correct
Q.62 Unattempt
The energy levels of an hydrogen atom are shown below. The transition corresponding to emission of shortest wavelength is

[6-Apr-2023 shift 1]
The energy levels of an hydrogen atom are shown below. The transition corresponding to emission of shortest wavelength is

[6-Apr-2023 shift 1]
Q.63 Correct
Q.63 In-correct
Q.63 Unattempt
The radius of fifth orbit of the Li++is _______ ×10−12m Take : radius of hydrogen atom =0.51Å
[6-Apr-2023 shift 1]
The radius of fifth orbit of the Li++is _______ ×10−12m Take : radius of hydrogen atom =0.51Å
[6-Apr-2023 shift 1]
Q.64 Correct
Q.64 In-correct
Q.64 Unattempt
The ratio of wavelength of spectral lines Hα and Hβ in the Balmer series is ‌
x
20
. The value of x is
[8-Apr-2023 shift 2]
The ratio of wavelength of spectral lines Hα and Hβ in the Balmer series is ‌
x
20
. The value of x is
[8-Apr-2023 shift 2]
Q.65 Correct
Q.65 In-correct
Q.65 Unattempt
The angular momentum for the electron in Bohr's orbit is L. If the electron is assumed to revolve in second orbit of hydrogen atom, them the change in angular momentum will be
[10-Apr-2023 shift 1]
The angular momentum for the electron in Bohr's orbit is L. If the electron is assumed to revolve in second orbit of hydrogen atom, them the change in angular momentum will be
[10-Apr-2023 shift 1]
Q.66 Correct
Q.66 In-correct
Q.66 Unattempt
If 917Å be the lowest wavelength of Lyman series then the lowest wavelength of Balmer series will be _______ Å
[10-Apr-2023 shift 2]
If 917Å be the lowest wavelength of Lyman series then the lowest wavelength of Balmer series will be _______ Å
[10-Apr-2023 shift 2]
Q.67 Correct
Q.67 In-correct
Q.67 Unattempt
A monochromatic light is incident on a hydrogen sample in ground state. Hydrogen atoms absorb a fraction of light and subsequently emit radiation of six different wavelengths. The frequency of incident light is x×1015 Hz. The value of x is _________.
(Given h=4.25×10−15‌eVs )
[11-Apr-2023 shift 1]
A monochromatic light is incident on a hydrogen sample in ground state. Hydrogen atoms absorb a fraction of light and subsequently emit radiation of six different wavelengths. The frequency of incident light is x×1015 Hz. The value of x is _________.
(Given h=4.25×10−15‌eVs )
[11-Apr-2023 shift 1]
Q.68 Correct
Q.68 In-correct
Q.68 Unattempt
The energy of He+ion in its first excited state is, (The ground state energy for the Hydrogen atom is −13.6‌eV ):
[11-Apr-2023 shift 2]
The energy of He+ion in its first excited state is, (The ground state energy for the Hydrogen atom is −13.6‌eV ):
[11-Apr-2023 shift 2]
Q.69 Correct
Q.69 In-correct
Q.69 Unattempt
A 12.5‌eV electron beam is used to bombard gaseous hydrogen at room temperature. The number of spectral lines emitted will be :
[12-Apr-2023 shift 1]
A 12.5‌eV electron beam is used to bombard gaseous hydrogen at room temperature. The number of spectral lines emitted will be :
[12-Apr-2023 shift 1]
Q.70 Correct
Q.70 In-correct
Q.70 Unattempt
The radius of 2‌nd ‌ orbit of He+of Bohr's model is r1 and that of fourth orbit of Be3+ is represented as r2. Now the ratio ‌
r2
r1
 is x:1. The value of x is __________
[13-Apr-2023 shift 1]
The radius of 2‌nd ‌ orbit of He+of Bohr's model is r1 and that of fourth orbit of Be3+ is represented as r2. Now the ratio ‌
r2
r1
 is x:1. The value of x is __________
[13-Apr-2023 shift 1]
Q.71 Correct
Q.71 In-correct
Q.71 Unattempt
An atom absorbs a photon of wavelength 500‌nm and emits another photon of wavelength 600‌nm. The net energy absorbed by the atom in this process is n×10−4‌eV. The value of n is [Assume the atom to be stationary during the absorption and emission process] (. Take h=6.6×10−34‌Js and c=3×108m∕ s)
[13-Apr-2023 shift 2]
An atom absorbs a photon of wavelength 500‌nm and emits another photon of wavelength 600‌nm. The net energy absorbed by the atom in this process is n×10−4‌eV. The value of n is [Assume the atom to be stationary during the absorption and emission process] (. Take h=6.6×10−34‌Js and c=3×108m∕ s)
[13-Apr-2023 shift 2]
Q.72 Correct
Q.72 In-correct
Q.72 Unattempt
As per given figure A, B and C are the first, second and third excited energy levels of hydrogen atom respectively. If the ratio of the two wavelengths (. i.e. ‌
λ1
λ2
) is ‌
7
4n
, then the value of n will be ________.


[15-Apr-2023 shift 1]
As per given figure A, B and C are the first, second and third excited energy levels of hydrogen atom respectively. If the ratio of the two wavelengths (. i.e. ‌
λ1
λ2
) is ‌
7
4n
, then the value of n will be ________.

[15-Apr-2023 shift 1]
Q.73 Correct
Q.73 In-correct
Q.73 Unattempt
For a nucleus ‌ZAX having mass number A and atomic number Z
A. The surface energy per nucleon (bs)=−a1A2∕3.
B. The Coulomb contribution to the binding energy bc=−a2‌
Z(Z−1)
A4∕3

C. The volume energy bv=a3A
D. Decrease in the binding energy is proportional to surface area.
E. While estimating the surface energy, it is assumed that each nucleon interacts with 12 nucleons. (a1,a2. and a3 are constants)
Choose the most appropriate answer from the options given below:
[8-Apr-2023 shift 1]
For a nucleus ‌ZAX having mass number A and atomic number Z
A. The surface energy per nucleon (bs)=−a1A2∕3.
B. The Coulomb contribution to the binding energy bc=−a2‌
Z(Z−1)
A4∕3

C. The volume energy bv=a3A
D. Decrease in the binding energy is proportional to surface area.
E. While estimating the surface energy, it is assumed that each nucleon interacts with 12 nucleons. (a1,a2. and a3 are constants)
Choose the most appropriate answer from the options given below:
[8-Apr-2023 shift 1]
Q.74 Correct
Q.74 In-correct
Q.74 Unattempt
A nucleus with mass number 242 and binding energy per nucleon as 7.6‌MeV breaks into two fragment each with mass number 121. If each fragment nucleus has binding energy per nucleon as 8.1‌MeV, the total gain in binding energy is ________ MeV.
[8-Apr-2023 shift 1]
A nucleus with mass number 242 and binding energy per nucleon as 7.6‌MeV breaks into two fragment each with mass number 121. If each fragment nucleus has binding energy per nucleon as 8.1‌MeV, the total gain in binding energy is ________ MeV.
[8-Apr-2023 shift 1]
Q.75 Correct
Q.75 In-correct
Q.75 Unattempt
A radio active material is reduced to 1∕8 of its original amount in 3 days. If 8×10−3‌kg of the material is left after 5 days the initial amount of the material is
[8-Apr-2023 shift 2]
A radio active material is reduced to 1∕8 of its original amount in 3 days. If 8×10−3‌kg of the material is left after 5 days the initial amount of the material is
[8-Apr-2023 shift 2]
Q.76 Correct
Q.76 In-correct
Q.76 Unattempt
The decay constant for a radioactive nuclide is 1.5×10−5 s−1. Atomic weight of the substance is 60gmole−1, (NA=6×1023). The activity of 1.0µg of the substance is _______ ×1010‌Bq.
[10-Apr-2023 shift 1]
The decay constant for a radioactive nuclide is 1.5×10−5 s−1. Atomic weight of the substance is 60gmole−1, (NA=6×1023). The activity of 1.0µg of the substance is _______ ×1010‌Bq.
[10-Apr-2023 shift 1]
Q.77 Correct
Q.77 In-correct
Q.77 Unattempt
The half life of a radioactive substance is T. The time taken, for disintegrating ‌
7
8
 th part of its original mass will be:
[10-Apr-2023 shift 2]
The half life of a radioactive substance is T. The time taken, for disintegrating ‌
7
8
 th part of its original mass will be:
[10-Apr-2023 shift 2]
Q.78 Correct
Q.78 In-correct
Q.78 Unattempt
Two radioactive elements A and B initially have same number of atoms. The half life of A is same as the average life of B. If λA and λB are decay constants of A and B respectively, then choose the correct relation from the given options.
[11-Apr-2023 shift 1]
Two radioactive elements A and B initially have same number of atoms. The half life of A is same as the average life of B. If λA and λB are decay constants of A and B respectively, then choose the correct relation from the given options.
[11-Apr-2023 shift 1]
Q.79 Correct
Q.79 In-correct
Q.79 Unattempt
A common example of alpha decay is
‌‌92238U→‌90234‌Th+‌2He4+Q
‌‌ Given : ‌
‌‌92238U=238.05060u,
‌‌234‌Th=234.04360u,
‌90
‌‌24‌He=4.00260u‌ and ‌
‌lu=931.5‌
MeV
c2

The energy released (Q) during the alpha decay of ‌238U is _______ MeV
[12-Apr-2023 shift 1]
A common example of alpha decay is
‌‌92238U→‌90234‌Th+‌2He4+Q
‌‌ Given : ‌
‌‌92238U=238.05060u,
‌‌234‌Th=234.04360u,
‌90
‌‌24‌He=4.00260u‌ and ‌
‌lu=931.5‌
MeV
c2

The energy released (Q) during the alpha decay of ‌238U is _______ MeV
[12-Apr-2023 shift 1]
Q.80 Correct
Q.80 In-correct
Q.80 Unattempt
‌92238A→‌90234B+‌24D+Q
In the given nuclear reaction, the approximate amount of energy released will be: [Given, mass of ‌92238A=238.05079×931.5‌MeV∕c2,
‌‌ mass of ‌‌90234B=234.04363×931.5‌MeV∕c2‌, ‌
‌‌ mass of ‌‌24D=4.00260×931.5‌MeV∕c2]
[13-Apr-2023 shift 1]
‌92238A→‌90234B+‌24D+Q
In the given nuclear reaction, the approximate amount of energy released will be: [Given, mass of ‌92238A=238.05079×931.5‌MeV∕c2,
‌‌ mass of ‌‌90234B=234.04363×931.5‌MeV∕c2‌, ‌
‌‌ mass of ‌‌24D=4.00260×931.5‌MeV∕c2]
[13-Apr-2023 shift 1]
Q.81 Correct
Q.81 In-correct
Q.81 Unattempt
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R
Assertion A : The binding energy per nucleon is practically independent of the atomic number for nuclei of mass number in the range 30 to 170 .
Reason R : Nuclear force is short ranged.
In the light of the above statements, choose the correct answer from the options given below
[13-Apr-2023 shift 2]
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R
Assertion A : The binding energy per nucleon is practically independent of the atomic number for nuclei of mass number in the range 30 to 170 .
Reason R : Nuclear force is short ranged.
In the light of the above statements, choose the correct answer from the options given below
[13-Apr-2023 shift 2]
Q.82 Correct
Q.82 In-correct
Q.82 Unattempt
The half-life of a radioactive nucleus is 5 years. The fraction of the original sample that would decay in 15 years is :
[15-Apr-2023 shift 1]
The half-life of a radioactive nucleus is 5 years. The fraction of the original sample that would decay in 15 years is :
[15-Apr-2023 shift 1]
Q.83 Correct
Q.83 In-correct
Q.83 Unattempt
Choose the correct option from the following options given below :
In the ground state of Rutherford's model electrons are in stable equilibrium. While in Thomson's
[24-Jun-2022-Shift-1]
Choose the correct option from the following options given below :
In the ground state of Rutherford's model electrons are in stable equilibrium. While in Thomson's
[24-Jun-2022-Shift-1]
Q.84 Correct
Q.84 In-correct
Q.84 Unattempt
In Bohr's atomic model of hydrogen, let K, P and E are the kinetic energy, potential energy and total energy of the electron respectively. Choose the correct option when the electron undergoes transitions to a higher level :
[24-Jun-2022-Shift-2]
In Bohr's atomic model of hydrogen, let K, P and E are the kinetic energy, potential energy and total energy of the electron respectively. Choose the correct option when the electron undergoes transitions to a higher level :
[24-Jun-2022-Shift-2]
Q.85 Correct
Q.85 In-correct
Q.85 Unattempt
The ratio for the speed of the electron in the 3‌rd ‌ orbit of He+to the speed of the electron in the 3‌rd ‌ orbit of hydrogen atom will be :
[25-Jun-2022-Shift-1]
The ratio for the speed of the electron in the 3‌rd ‌ orbit of He+to the speed of the electron in the 3‌rd ‌ orbit of hydrogen atom will be :
[25-Jun-2022-Shift-1]
Q.86 Correct
Q.86 In-correct
Q.86 Unattempt
Which of the following figure represents the variation of ln(‌
R
R0
) with lnA (if R= radius of a nucleus and A= its mass number)
[25-Jun-2022-Shift-2]
Which of the following figure represents the variation of ln(‌
R
R0
) with lnA (if R= radius of a nucleus and A= its mass number)
[25-Jun-2022-Shift-2]
Q.87 Correct
Q.87 In-correct
Q.87 Unattempt
A hydrogen atom in its ground state absorbs 10.2‌eV of energy. The angular momentum of electron of the hydrogen atom will increase by the value of :
(Given, Planck's constant =6.6×10−34‌Js ).
[27-Jun-2022-Shift-1]
A hydrogen atom in its ground state absorbs 10.2‌eV of energy. The angular momentum of electron of the hydrogen atom will increase by the value of :
(Given, Planck's constant =6.6×10−34‌Js ).
[27-Jun-2022-Shift-1]
Q.88 Correct
Q.88 In-correct
Q.88 Unattempt
A beam of monochromatic light is used to excite the electron in Li++from the first orbit to the third orbit. The wavelength of monochromatic light is found to be x×10−10m. The value of x is____
[Given hc =1242‌eV‌nm]
[27-Jun-2022-Shift-1]
A beam of monochromatic light is used to excite the electron in Li++from the first orbit to the third orbit. The wavelength of monochromatic light is found to be x×10−10m. The value of x is____
[Given hc =1242‌eV‌nm]
[27-Jun-2022-Shift-1]
Q.89 Correct
Q.89 In-correct
Q.89 Unattempt
√d1 and √d2 are the impact parameters corresponding to scattering angles 60∘ and 90∘ respectively, when an α particle is approaching a gold nucleus. For d1=xd2, the value of x will be_____
[29-Jun-2022-Shift-1]
√d1 and √d2 are the impact parameters corresponding to scattering angles 60∘ and 90∘ respectively, when an α particle is approaching a gold nucleus. For d1=xd2, the value of x will be_____
[29-Jun-2022-Shift-1]
Q.90 Correct
Q.90 In-correct
Q.90 Unattempt
Nucleus A is having mass number 220 and its binding energy per nucleon is 5.6‌MeV. It splits in two fragments ' B ' and ' C ' of mass numbers 105 and 115 . The binding energy of nucleons in ' B ' and ' C ' is 6.4‌MeV per nucleon. The energy Q released per fission will be :
[24-Jun-2022-Shift-1]
Nucleus A is having mass number 220 and its binding energy per nucleon is 5.6‌MeV. It splits in two fragments ' B ' and ' C ' of mass numbers 105 and 115 . The binding energy of nucleons in ' B ' and ' C ' is 6.4‌MeV per nucleon. The energy Q released per fission will be :
[24-Jun-2022-Shift-1]
Q.91 Correct
Q.91 In-correct
Q.91 Unattempt
A sample contains 10−2‌kg each of two substances A and B with half lives 4s and 8 s respectively. The ratio of their atomic weights is 1:2. The ratio of the amounts of A and B after 16s is ‌
x
100
. The value of x is_____
[24-Jun-2022-Shift-2]
A sample contains 10−2‌kg each of two substances A and B with half lives 4s and 8 s respectively. The ratio of their atomic weights is 1:2. The ratio of the amounts of A and B after 16s is ‌
x
100
. The value of x is_____
[24-Jun-2022-Shift-2]
Q.92 Correct
Q.92 In-correct
Q.92 Unattempt
How many alpha and beta particles are emitted when Uranium ‌92U238 decays to lead ‌82Pb206 ?
[26-Jun-2022-Shift-1]
How many alpha and beta particles are emitted when Uranium ‌92U238 decays to lead ‌82Pb206 ?
[26-Jun-2022-Shift-1]
Q.93 Correct
Q.93 In-correct
Q.93 Unattempt
A radioactive nucleus can decay by two different processes. Half-life for the first process is 3.0 hours while it is 4.5 hours for the second process. The effective half-life of the nucleus will be:
[26-Jun-2022-Shift-2]
A radioactive nucleus can decay by two different processes. Half-life for the first process is 3.0 hours while it is 4.5 hours for the second process. The effective half-life of the nucleus will be:
[26-Jun-2022-Shift-2]
Q.94 Correct
Q.94 In-correct
Q.94 Unattempt
The Q-value of a nuclear reaction and kinetic energy of the projectile particle, Kp are related as :
[28-Jun-2022-Shift-1]
The Q-value of a nuclear reaction and kinetic energy of the projectile particle, Kp are related as :
[28-Jun-2022-Shift-1]
Q.95 Correct
Q.95 In-correct
Q.95 Unattempt
Following statements related to radioactivity are given below :
(A) Radioactivity is a random and spontaneous process and is dependent on physical and chemical conditions.
(B) The number of un-decayed nuclei in the radioactive sample decays exponentially with time.
(C) Slope of the graph of loge (no. of undecayed nuclei) Vs. time represents the reciprocal of mean life time (τ).
(D) Product of decay constant (λ) and half-life time (T1∕2) is not constant.
Choose the most appropriate answer from the options given below :
[28-Jun-2022-Shift-2]
Following statements related to radioactivity are given below :
(A) Radioactivity is a random and spontaneous process and is dependent on physical and chemical conditions.
(B) The number of un-decayed nuclei in the radioactive sample decays exponentially with time.
(C) Slope of the graph of loge (no. of undecayed nuclei) Vs. time represents the reciprocal of mean life time (τ).
(D) Product of decay constant (λ) and half-life time (T1∕2) is not constant.
Choose the most appropriate answer from the options given below :
[28-Jun-2022-Shift-2]
Q.96 Correct
Q.96 In-correct
Q.96 Unattempt
The activity of a radioactive material is 2.56×10−3 Ci. If the half life of the material is 5 days, after how many days the activity will become 2×10−5‌Ci ?
[29-Jun-2022-Shift-1]
The activity of a radioactive material is 2.56×10−3 Ci. If the half life of the material is 5 days, after how many days the activity will become 2×10−5‌Ci ?
[29-Jun-2022-Shift-1]
Q.97 Correct
Q.97 In-correct
Q.97 Unattempt
In the following nuclear reaction,
D
α
⟶
D1
β−
⟶
D2
α
⟶
D3
γ
⟶
D4
Mass number of D is 182 and atomic number is 74 . Mass number and atomic number of D4 respectively will be____
[29-Jun-2022-Shift-2]
In the following nuclear reaction,
D
α
⟶
D1
β−
⟶
D2
α
⟶
D3
γ
⟶
D4
Mass number of D is 182 and atomic number is 74 . Mass number and atomic number of D4 respectively will be____
[29-Jun-2022-Shift-2]
Q.98 Correct
Q.98 In-correct
Q.98 Unattempt
The half life of a radioactive substance is 5 years. After x years a given sample of the radioactive substance gets reduced to 6.25% of its initial value. The value of x is____
[29-Jun-2022-Shift-2]
The half life of a radioactive substance is 5 years. After x years a given sample of the radioactive substance gets reduced to 6.25% of its initial value. The value of x is____
[29-Jun-2022-Shift-2]
Q.99 Correct
Q.99 In-correct
Q.99 Unattempt
The momentum of an electron revolving in n‌th ‌ orbit is given by:
(Symbols have their usual meanings)
[25-Jul-2022-Shift-1]
The momentum of an electron revolving in n‌th ‌ orbit is given by:
(Symbols have their usual meanings)
[25-Jul-2022-Shift-1]
Q.100 Correct
Q.100 In-correct
Q.100 Unattempt
The magnetic moment of an electron (e) revolving in an orbit around nucleus with an orbital angular momentum is given by :
[25-Jul-2022-Shift-1]
The magnetic moment of an electron (e) revolving in an orbit around nucleus with an orbital angular momentum is given by :
[25-Jul-2022-Shift-1]
Q.101 Correct
Q.101 In-correct
Q.101 Unattempt
Hydrogen atom from excited state comes to the ground state by emitting a photon of wavelength λ. The value of principal quantum number ' n ' of the excited state will be : (R : Rydberg constant)
[25-Jul-2022-Shift-2]
Hydrogen atom from excited state comes to the ground state by emitting a photon of wavelength λ. The value of principal quantum number ' n ' of the excited state will be : (R : Rydberg constant)
[25-Jul-2022-Shift-2]
Q.102 Correct
Q.102 In-correct
Q.102 Unattempt
‌
x
x+4
 is the ratio of energies of photons produced due to transition of an electron of hydrogen atom from its
(i) third permitted energy level to the second level and
(ii) the highest permitted energy level to the second permitted level.
The value of x will be
[25-Jul-2022-Shift-2]
‌
x
x+4
 is the ratio of energies of photons produced due to transition of an electron of hydrogen atom from its
(i) third permitted energy level to the second level and
(ii) the highest permitted energy level to the second permitted level.
The value of x will be
[25-Jul-2022-Shift-2]
Q.103 Correct
Q.103 In-correct
Q.103 Unattempt
In the hydrogen spectrum, λ be the wavelength of first transition line of Lyman series. The wavelength difference will be "a λ ' between the wavelength of 3rd transition line of Paschen series and that of 2‌nd ‌ transition line of Balmer series where a= _________.
[26-Jul-2022-Shift-1]
In the hydrogen spectrum, λ be the wavelength of first transition line of Lyman series. The wavelength difference will be "a λ ' between the wavelength of 3rd transition line of Paschen series and that of 2‌nd ‌ transition line of Balmer series where a= _________.
[26-Jul-2022-Shift-1]
Q.104 Correct
Q.104 In-correct
Q.104 Unattempt
A nucleus of mass M at rest splits into two parts having masses ‌
M′
3
 and ‌
2M′
3
(M′<M). The ratio of de Broglie wavelength of two parts will be :
[26-Jul-2022-Shift-2]
A nucleus of mass M at rest splits into two parts having masses ‌
M′
3
 and ‌
2M′
3
(M′<M). The ratio of de Broglie wavelength of two parts will be :
[26-Jul-2022-Shift-2]
Q.105 Correct
Q.105 In-correct
Q.105 Unattempt
Mass numbers of two nuclei are in the ratio of 4:3. Their nuclear densities will be in the ratio of
[26-Jul-2022-Shift-2]
Mass numbers of two nuclei are in the ratio of 4:3. Their nuclear densities will be in the ratio of
[26-Jul-2022-Shift-2]
Q.106 Correct
Q.106 In-correct
Q.106 Unattempt
An electron (mass m ) with an initial velocity
→
v
=v0i(v0>0) is moving in an electric field
→
E
=−E0
∧
i
(E0>0) where E0 is constant. If at t=0 de Broglie wavelength is λ0=‌
h
mv0
, then its de Broglie wavelength after time t is given by
[27-Jul-2022-Shift-1]
An electron (mass m ) with an initial velocity
→
v
=v0i(v0>0) is moving in an electric field
→
E
=−E0
∧
i
(E0>0) where E0 is constant. If at t=0 de Broglie wavelength is λ0=‌
h
mv0
, then its de Broglie wavelength after time t is given by
[27-Jul-2022-Shift-1]
Q.107 Correct
Q.107 In-correct
Q.107 Unattempt
Find the ratio of energies of photons produced due to transition of an electron of hydrogen atom from its (i) second permitted energy level to the first level, and (ii) the highest permitted energy level to the first permitted level.
[29-Jul-2022-Shift-1]
Find the ratio of energies of photons produced due to transition of an electron of hydrogen atom from its (i) second permitted energy level to the first level, and (ii) the highest permitted energy level to the first permitted level.
[29-Jul-2022-Shift-1]
Q.108 Correct
Q.108 In-correct
Q.108 Unattempt
Read the following statements:
(A) Volume of the nucleus is directly proportional to the mass number.
(B) Volume of the nucleus is independent of mass number.
(C) Density of the nucleus is directly proportional to the mass number.
(D) Density of the nucleus is directly proportional to the cube root of the mass number.
(E) Density of the nucleus is independent of the mass number.
Choose the correct option from the following options.
[29-Jul-2022-Shift-2]
Read the following statements:
(A) Volume of the nucleus is directly proportional to the mass number.
(B) Volume of the nucleus is independent of mass number.
(C) Density of the nucleus is directly proportional to the mass number.
(D) Density of the nucleus is directly proportional to the cube root of the mass number.
(E) Density of the nucleus is independent of the mass number.
Choose the correct option from the following options.
[29-Jul-2022-Shift-2]
Q.109 Correct
Q.109 In-correct
Q.109 Unattempt
The disintegration rate of a certain radioactive sample at any instant is 4250 disintegrations per minute. 10 minutes later, the rate becomes 2250 disintegrations per minute. The approximate decay constant is :
(Take log101.88=0.274)
[26-Jul-2022-Shift-1]
The disintegration rate of a certain radioactive sample at any instant is 4250 disintegrations per minute. 10 minutes later, the rate becomes 2250 disintegrations per minute. The approximate decay constant is :
(Take log101.88=0.274)
[26-Jul-2022-Shift-1]
Q.110 Correct
Q.110 In-correct
Q.110 Unattempt
Two lighter nuclei combine to form a comparatively heavier nucleus by the relation given below :
‌12X+‌12X=‌24Y
The binding energies per nucleon for ‌
2
1
X and ‌24Y are 1.1‌MeV and 7.6‌MeV respectively. The energy released in this process is _________ MeV
[26-Jul-2022-Shift-2]
Two lighter nuclei combine to form a comparatively heavier nucleus by the relation given below :
‌12X+‌12X=‌24Y
The binding energies per nucleon for ‌
2
1
X and ‌24Y are 1.1‌MeV and 7.6‌MeV respectively. The energy released in this process is _________ MeV
[26-Jul-2022-Shift-2]
Q.111 Correct
Q.111 In-correct
Q.111 Unattempt
What is the half-life period of a radioactive material if its activity drops to 1∕16‌th ‌ of its initial value in 30 years?
[27-Jul-2022-Shift-1]
What is the half-life period of a radioactive material if its activity drops to 1∕16‌th ‌ of its initial value in 30 years?
[27-Jul-2022-Shift-1]
Q.112 Correct
Q.112 In-correct
Q.112 Unattempt
The activity of a radioactive material is 6.4×10−4 curie. Its half life is 5 days. The activity will become 5×10−6 curie after :
[27-Jul-2022-Shift-2]
The activity of a radioactive material is 6.4×10−4 curie. Its half life is 5 days. The activity will become 5×10−6 curie after :
[27-Jul-2022-Shift-2]
Q.113 Correct
Q.113 In-correct
Q.113 Unattempt
The half life period of a radioactive substance is 60 days. The time taken for ‌
7
8
 th of its original mass to disintegrate will be :
[28-Jul-2022-Shift-1]
The half life period of a radioactive substance is 60 days. The time taken for ‌
7
8
 th of its original mass to disintegrate will be :
[28-Jul-2022-Shift-1]
Q.114 Correct
Q.114 In-correct
Q.114 Unattempt
A freshly prepared radioactive source of half life 2 hours 30 minutes emits radiation which is 64 times the permissible safe level. The minimum time, after which it would be possible to work safely with source, will be _______ hours.
[28-Jul-2022-Shift-1]
A freshly prepared radioactive source of half life 2 hours 30 minutes emits radiation which is 64 times the permissible safe level. The minimum time, after which it would be possible to work safely with source, will be _______ hours.
[28-Jul-2022-Shift-1]
Q.115 Correct
Q.115 In-correct
Q.115 Unattempt
A radioactive sample decays ‌
7
8
 times its original quantity in 15 minutes. The half-life of the sample is
[28-Jul-2022-Shift-2]
A radioactive sample decays ‌
7
8
 times its original quantity in 15 minutes. The half-life of the sample is
[28-Jul-2022-Shift-2]
Q.116 Correct
Q.116 In-correct
Q.116 Unattempt
Two radioactive materials A and B have decay constants 25λ and 16λ respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of B to that of A will be "e" after a time ‌
1
aλ
. The value of a is _______.
[29-Jul-2022-Shift-2]
Two radioactive materials A and B have decay constants 25λ and 16λ respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of B to that of A will be "e" after a time ‌
1
aλ
. The value of a is _______.
[29-Jul-2022-Shift-2]
Q.117 Correct
Q.117 In-correct
Q.117 Unattempt
The recoil speed of a hydrogen atom after it emits a photon in going from n=5 state to n=1 state will be
[26 Feb 2021 Shift 2]
The recoil speed of a hydrogen atom after it emits a photon in going from n=5 state to n=1 state will be
[26 Feb 2021 Shift 2]
Q.118 Correct
Q.118 In-correct
Q.118 Unattempt
If λ1 and λ2 are the wavelengths of the third member of Lyman and first member of the Paschen series respectively, then the value of λ1:λ2 is
[26 Feb 2021 Shift 1]
If λ1 and λ2 are the wavelengths of the third member of Lyman and first member of the Paschen series respectively, then the value of λ1:λ2 is
[26 Feb 2021 Shift 1]
Q.119 Correct
Q.119 In-correct
Q.119 Unattempt
The wavelength of the photon emitted by a hydrogen atom when an electron makes a transition from n=2 to n=1 state is
[25 Feb 2021 Shift 2]
The wavelength of the photon emitted by a hydrogen atom when an electron makes a transition from n=2 to n=1 state is
[25 Feb 2021 Shift 2]
Q.120 Correct
Q.120 In-correct
Q.120 Unattempt
According to Bohr atom model, in which of the following transitions will the frequency be maximum ?
[24 Feb 2021 Shift 2]
According to Bohr atom model, in which of the following transitions will the frequency be maximum ?
[24 Feb 2021 Shift 2]
Q.121 Correct
Q.121 In-correct
Q.121 Unattempt
A radioactive sample is undergoing α-decay. At any time t1, its activity is A and another time t2, the activity is ‌
A
5
. What is the average life time for the sample?
[26 Feb 2021 Shift 2]
A radioactive sample is undergoing α-decay. At any time t1, its activity is A and another time t2, the activity is ‌
A
5
. What is the average life time for the sample?
[26 Feb 2021 Shift 2]
Q.122 Correct
Q.122 In-correct
Q.122 Unattempt
Two radioactive substances X and Y originally have N1 and N2 nuclei, respectively. Half-life of X is half of the half-life of Y. After three half-lives of Y, number of nuclei of both are equal. The ratio ‌
N1
N2
 will be equal to
[25 Feb 2021 Shift 1]
Two radioactive substances X and Y originally have N1 and N2 nuclei, respectively. Half-life of X is half of the half-life of Y. After three half-lives of Y, number of nuclei of both are equal. The ratio ‌
N1
N2
 will be equal to
[25 Feb 2021 Shift 1]
Q.123 Correct
Q.123 In-correct
Q.123 Unattempt
In the given figure, the energy levels of hydrogen atom have been shown along with some transitions marked A, B, C, D and E. The transitions A, B and C respectively represent :

[24feb2021shift1]
In the given figure, the energy levels of hydrogen atom have been shown along with some transitions marked A, B, C, D and E. The transitions A, B and C respectively represent :

[24feb2021shift1]
Q.124 Correct
Q.124 In-correct
Q.124 Unattempt
Imagine that the electron in a hydrogen atom is replaced by a muon (µ). The mass of muon particle is 207 times that of an electron and charge is equal to the charge of an electron. The ionisation potential of this hydrogen atom will be
[18 Mar 2021 Shift 1]
Imagine that the electron in a hydrogen atom is replaced by a muon (µ). The mass of muon particle is 207 times that of an electron and charge is equal to the charge of an electron. The ionisation potential of this hydrogen atom will be
[18 Mar 2021 Shift 1]
Q.125 Correct
Q.125 In-correct
Q.125 Unattempt
The atomic hydrogen emits a line spectrum consisting of various series. Which series of hydrogen atomic spectra is lying in the visible region?
[17 Mar 2021 Shift 2]
The atomic hydrogen emits a line spectrum consisting of various series. Which series of hydrogen atomic spectra is lying in the visible region?
[17 Mar 2021 Shift 2]
Q.126 Correct
Q.126 In-correct
Q.126 Unattempt
A particle of mass m moves in a circular orbit in a central potential field U(r)=U0r4. If Bohr's quantisation conditions are applied, radii of possible orbitals rn vary with n1∕α, where α is
[17 Mar 2021 Shift 2]
A particle of mass m moves in a circular orbit in a central potential field U(r)=U0r4. If Bohr's quantisation conditions are applied, radii of possible orbitals rn vary with n1∕α, where α is
[17 Mar 2021 Shift 2]
Q.127 Correct
Q.127 In-correct
Q.127 Unattempt
Which level of the single ionized carbon has the same energy as the ground state energy of hydrogen atom?
[17 Mar 2021 Shift 1]
Which level of the single ionized carbon has the same energy as the ground state energy of hydrogen atom?
[17 Mar 2021 Shift 1]
Q.128 Correct
Q.128 In-correct
Q.128 Unattempt
If an electron is moving in the nth orbit of the hydrogen atom, then its velocity vn for the nth orbit is given as
[17 Mar 2021 Shift 1]
If an electron is moving in the nth orbit of the hydrogen atom, then its velocity vn for the nth orbit is given as
[17 Mar 2021 Shift 1]
Q.129 Correct
Q.129 In-correct
Q.129 Unattempt
The first three spectral lines of H-atom in the Balmer series are given λ1,λ2,λ3 considering the Bohr atomic model, the wavelengths of first and third spectral lines (‌
λ1
λ3
) are related by a factor of approximately x×10−1. The value of x to the nearest integer, is ..........
[16 Mar 2021 Shift 1]
The first three spectral lines of H-atom in the Balmer series are given λ1,λ2,λ3 considering the Bohr atomic model, the wavelengths of first and third spectral lines (‌
λ1
λ3
) are related by a factor of approximately x×10−1. The value of x to the nearest integer, is ..........
[16 Mar 2021 Shift 1]
Q.130 Correct
Q.130 In-correct
Q.130 Unattempt
The decay of a proton to neutron is
[18 Mar 2021 Shift 2]
The decay of a proton to neutron is
[18 Mar 2021 Shift 2]
Q.131 Correct
Q.131 In-correct
Q.131 Unattempt
A radioactive sample disintegrates via two independent decay processes having half-lives T1∕2(1) and T1∕2(2), respectively. The effective half-life T1∕2 of the nuclei is
[18 Mar 2021 Shift 1]
A radioactive sample disintegrates via two independent decay processes having half-lives T1∕2(1) and T1∕2(2), respectively. The effective half-life T1∕2 of the nuclei is
[18 Mar 2021 Shift 1]
Q.132 Correct
Q.132 In-correct
Q.132 Unattempt
Amplitude of a mass-spring system, which is executing simple harmonic motion decreases with time. If mass =500g, decay constant =20g/s, then how much time is required for the amplitude of the system to drop to half of its initial value? (ln‌2=0.693)
[16 Mar 2021 Shift 2]
Amplitude of a mass-spring system, which is executing simple harmonic motion decreases with time. If mass =500g, decay constant =20g/s, then how much time is required for the amplitude of the system to drop to half of its initial value? (ln‌2=0.693)
[16 Mar 2021 Shift 2]
Q.133 Correct
Q.133 In-correct
Q.133 Unattempt
Calculate the time interval between 33% decay and 67% decay if half-life of a substance is 20min.
[16 Mar 2021 Shift 2]
Calculate the time interval between 33% decay and 67% decay if half-life of a substance is 20min.
[16 Mar 2021 Shift 2]
Q.134 Correct
Q.134 In-correct
Q.134 Unattempt
The half-life of Au198 is 2.7 days. The activity of 1.50mg of Au198 if its atomic weight is 198gmol−1 is (NA=6×1023∕mol)
[16 Mar 2021 Shift 2]
The half-life of Au198 is 2.7 days. The activity of 1.50mg of Au198 if its atomic weight is 198gmol−1 is (NA=6×1023∕mol)
[16 Mar 2021 Shift 2]
Q.135 Correct
Q.135 In-correct
Q.135 Unattempt
The radiation corresponding to 3→2 transition of a hydrogen atom falls on a gold surface to generate photoelectrons. These electrons are passed through a magnetic field of 5×10−4T. Assume that the radius of the largest circular path followed by these electrons is 7mm, the work function of the metal is:
(Mass of electron =9.1×10−31kg )
[20 Jul 2021 Shift 1]
The radiation corresponding to 3→2 transition of a hydrogen atom falls on a gold surface to generate photoelectrons. These electrons are passed through a magnetic field of 5×10−4T. Assume that the radius of the largest circular path followed by these electrons is 7mm, the work function of the metal is:
(Mass of electron =9.1×10−31kg )
[20 Jul 2021 Shift 1]
Q.136 Correct
Q.136 In-correct
Q.136 Unattempt
The Kα X-ray of molybdenum has wavelength0.071nm. If the energy of a molybdenum atoms with a K electron knocked out is 27.5keV, the energy of this atom when an L electron is knocked out will be ______ keV. (Round off to the nearest integer)
[h=4.14×10−15eVs,c=3×108ms−1]
[27 Jul 2021 Shift 2]
The Kα X-ray of molybdenum has wavelength0.071nm. If the energy of a molybdenum atoms with a K electron knocked out is 27.5keV, the energy of this atom when an L electron is knocked out will be ______ keV. (Round off to the nearest integer)
[h=4.14×10−15eVs,c=3×108ms−1]
[27 Jul 2021 Shift 2]
Q.137 Correct
Q.137 In-correct
Q.137 Unattempt
An electron and proton are separated by a large distance. The electron starts approaching the proton with energy 3 eV. The proton captures the electrons and forms a hydrogen atom in second excited state. The resulting photon is incident on a photosensitive metal of threshold wavelength 4000 Å. What is the maximum kinetic energy of the emitted photoelectron?
[27 Jul 2021 Shift 2]
An electron and proton are separated by a large distance. The electron starts approaching the proton with energy 3 eV. The proton captures the electrons and forms a hydrogen atom in second excited state. The resulting photon is incident on a photosensitive metal of threshold wavelength 4000 Å. What is the maximum kinetic energy of the emitted photoelectron?
[27 Jul 2021 Shift 2]
Q.138 Correct
Q.138 In-correct
Q.138 Unattempt
Consider the following statements :
A. Atoms of each element emit characteristics spectrum.
B. According to Bohr's Postulate, an electron in a hydrogen atom, revolves in a certain stationary orbit.
C. The density of nuclear matter depends on the size of the nucleus.
D. A free neutron is stable but a free proton decay is possible.
E. Radioactivity is an indication of the instability of nuclei.
Choose the correct answer from the options given below :
[27 Jul 2021 Shift 2]
Consider the following statements :
A. Atoms of each element emit characteristics spectrum.
B. According to Bohr's Postulate, an electron in a hydrogen atom, revolves in a certain stationary orbit.
C. The density of nuclear matter depends on the size of the nucleus.
D. A free neutron is stable but a free proton decay is possible.
E. Radioactivity is an indication of the instability of nuclei.
Choose the correct answer from the options given below :
[27 Jul 2021 Shift 2]
Q.139 Correct
Q.139 In-correct
Q.139 Unattempt
A radioactive sample has an average life of 30 ms and is decaying. A capacitor of capacitance 200 µF is first charged and later connected with resistor 'R'. If the ratio of charge on capacitor to the activity of radioactive sample is fixed with respect to time then the value of 'R' should be ______Ω.
[27 Jul 2021 Shift 1]
A radioactive sample has an average life of 30 ms and is decaying. A capacitor of capacitance 200 µF is first charged and later connected with resistor 'R'. If the ratio of charge on capacitor to the activity of radioactive sample is fixed with respect to time then the value of 'R' should be ______Ω.
[27 Jul 2021 Shift 1]
Q.140 Correct
Q.140 In-correct
Q.140 Unattempt
If ' f denotes the ratio of the number of nuclei decayed (Nd) to the number of nuclei at t=0(N0)then for a collection of radioactive nuclei, the rate of change of f′ with respect to time is given as :
[λ is the radioactive decay constant]
[27 Jul 2021 Shift 1]
If ' f denotes the ratio of the number of nuclei decayed (Nd) to the number of nuclei at t=0(N0)then for a collection of radioactive nuclei, the rate of change of f′ with respect to time is given as :
[λ is the radioactive decay constant]
[27 Jul 2021 Shift 1]
Q.141 Correct
Q.141 In-correct
Q.141 Unattempt
The nuclear activity of a radioactive element becomes (
1
8
)th of its initial value in 30 years. The half-life of radioactive element is ________ years.
[25 Jul 2021 Shift 2]
The nuclear activity of a radioactive element becomes (
1
8
)th of its initial value in 30 years. The half-life of radioactive element is ________ years.
[25 Jul 2021 Shift 2]
Q.142 Correct
Q.142 In-correct
Q.142 Unattempt
For a certain radioactive process the graph between In R and t(sec) is obtained as shown in the figure.
Then the value of half life for the unknown radioactive material is approximately :

[20 Jul 2021 Shift 2]
For a certain radioactive process the graph between In R and t(sec) is obtained as shown in the figure.
Then the value of half life for the unknown radioactive material is approximately :

[20 Jul 2021 Shift 2]
Q.143 Correct
Q.143 In-correct
Q.143 Unattempt
A radioactive substance decays to (
1
16
)th of its initial activity in 80 days. The half life of the radioactive substance expressed in days is ______.
[20 Jul 2021 Shift 2]
A radioactive substance decays to (
1
16
)th of its initial activity in 80 days. The half life of the radioactive substance expressed in days is ______.
[20 Jul 2021 Shift 2]
Q.144 Correct
Q.144 In-correct
Q.144 Unattempt
A radioactive material decays by simultaneous emissions of two particles with half lives of 1400 years and 700 years respectively. What will be the time after the which one third of the material remains ? (Take ln 3 = 1.1)
[20 Jul 2021 Shift 1]
A radioactive material decays by simultaneous emissions of two particles with half lives of 1400 years and 700 years respectively. What will be the time after the which one third of the material remains ? (Take ln 3 = 1.1)
[20 Jul 2021 Shift 1]
Q.145 Correct
Q.145 In-correct
Q.145 Unattempt
From the given data, the amount of energy required to break the nucleus of aluminium ‌1327Al is _____ x×10−3J
Mass of neutron =1.00866u
Mass of proton =1.00726u
Mass of Aluminium nucleus =27.18846u
(Assume 1 u corresponds to x J of energy)
(Round off to the nearest integer)
[25 Jul 2021 Shift 2]
From the given data, the amount of energy required to break the nucleus of aluminium ‌1327Al is _____ x×10−3J
Mass of neutron =1.00866u
Mass of proton =1.00726u
Mass of Aluminium nucleus =27.18846u
(Assume 1 u corresponds to x J of energy)
(Round off to the nearest integer)
[25 Jul 2021 Shift 2]
Q.146 Correct
Q.146 In-correct
Q.146 Unattempt
A nucleus with mass number 184 initially at rest emits an α-particle. If the Q value of the reaction is 5.5MeV, calculate the kinetic energy of the α− particle.
[22 Jul 2021 Shift 2]
A nucleus with mass number 184 initially at rest emits an α-particle. If the Q value of the reaction is 5.5MeV, calculate the kinetic energy of the α− particle.
[22 Jul 2021 Shift 2]
Q.147 Correct
Q.147 In-correct
Q.147 Unattempt
A nucleus of mass M emits γ-ray photon of frequency 'v′. The loss of internal energy by the nucleus is :
[Take 'c' as the speed of electromagnetic wave]
[20 Jul 2021 Shift 1]
A nucleus of mass M emits γ-ray photon of frequency 'v′. The loss of internal energy by the nucleus is :
[Take 'c' as the speed of electromagnetic wave]
[20 Jul 2021 Shift 1]
Q.148 Correct
Q.148 In-correct
Q.148 Unattempt
x different wavelengths may be observed in the spectrum from a hydrogen sample if the atoms are exited to states with principal quantum number n=6 ? The value of x is .......... .
[27 Aug 2021 Shift 2]
x different wavelengths may be observed in the spectrum from a hydrogen sample if the atoms are exited to states with principal quantum number n=6 ? The value of x is .......... .
[27 Aug 2021 Shift 2]
Q.149 Correct
Q.149 In-correct
Q.149 Unattempt
A free electron of 2.6‌eV energy collides with aH+ ion. This results in the formation of a hydrogen atom in the first excited state and a photon is released. Find the frequency of the emitted photon.
(h=6.6×10−34‌Js)
[31 Aug 2021 Shift 2]
A free electron of 2.6‌eV energy collides with aH+ ion. This results in the formation of a hydrogen atom in the first excited state and a photon is released. Find the frequency of the emitted photon.
(h=6.6×10−34‌Js)
[31 Aug 2021 Shift 2]
Q.150 Correct
Q.150 In-correct
Q.150 Unattempt
A particular hydrogen like ion emits radiation of frequency 2.92×1015‌Hz when it makes transition from n=3 to n=1. The frequency in Hz of radiation emitted in transition from n=2 to n=1 will be
[26 Aug 2021 Shift 1]
A particular hydrogen like ion emits radiation of frequency 2.92×1015‌Hz when it makes transition from n=3 to n=1. The frequency in Hz of radiation emitted in transition from n=2 to n=1 will be
[26 Aug 2021 Shift 1]
Q.151 Correct
Q.151 In-correct
Q.151 Unattempt
A sample of a radioactive nucleus A disintegrates to another radioactive nucleus B, which in turn disintegrates to some other stable nucleus C. Plot of a graph showing the variation of number of atoms of nucleus B versus time is
(Assume that at t = 0, there are no B atoms in the sample)
[31 Aug 2021 Shift 1]
A sample of a radioactive nucleus A disintegrates to another radioactive nucleus B, which in turn disintegrates to some other stable nucleus C. Plot of a graph showing the variation of number of atoms of nucleus B versus time is
(Assume that at t = 0, there are no B atoms in the sample)
[31 Aug 2021 Shift 1]
Q.152 Correct
Q.152 In-correct
Q.152 Unattempt
There are 1010 radioactive nuclei in a given radioactive element. Its half-life time is 1‌min. How many nuclei will remain after 30 s?
(√2=1.414)
[27 Aug 2021 Shift 1]
There are 1010 radioactive nuclei in a given radioactive element. Its half-life time is 1‌min. How many nuclei will remain after 30 s?
(√2=1.414)
[27 Aug 2021 Shift 1]
Q.153 Correct
Q.153 In-correct
Q.153 Unattempt
At time t = 0, a material is composed of two radioactive atoms A and B , where NA(0)=2NB(0). The decay constant of both kind of radioactive atoms is λ. However, A disintegrates to B and B disintegrates to C. Which of the following figures represents the evolution of
NB(t)
NB(0)
 with respect to time t ?
[NA(0)= Number of A atoms at t = 0]
[NB(0)= Number of B atoms at t = 0]
[26 Aug 2021 Shift 2]
At time t = 0, a material is composed of two radioactive atoms A and B , where NA(0)=2NB(0). The decay constant of both kind of radioactive atoms is λ. However, A disintegrates to B and B disintegrates to C. Which of the following figures represents the evolution of
NB(t)
NB(0)
 with respect to time t ?
[NA(0)= Number of A atoms at t = 0]
[NB(0)= Number of B atoms at t = 0]
[26 Aug 2021 Shift 2]
Q.154 Correct
Q.154 In-correct
Q.154 Unattempt
The graph which depicts the results of Rutherford gold foil experiment with
α-particles is:
θ : Scattering angle
α : Number of scattered a-particles detected
(Plots are schematic and not to scale)
[8 Jan. 2020 I]
The graph which depicts the results of Rutherford gold foil experiment with
α-particles is:
θ : Scattering angle
α : Number of scattered a-particles detected
(Plots are schematic and not to scale)
[8 Jan. 2020 I]
Q.155 Correct
Q.155 In-correct
Q.155 Unattempt
The energy required to ionise a hydrogen like ion in its ground state is 9 Rydbergs. What is the wavelength of the radiation emitted when the electron in this ion jumps from the second excited state to the ground state?
[9 Jan. 2020 II]
The energy required to ionise a hydrogen like ion in its ground state is 9 Rydbergs. What is the wavelength of the radiation emitted when the electron in this ion jumps from the second excited state to the ground state?
[9 Jan. 2020 II]
Q.156 Correct
Q.156 In-correct
Q.156 Unattempt
The first member of the Balmer series of hydrogen atom has a wavelength of 6561 Å. The wavelength of the second member of the Balmer series (in nm) is ______.
[NA 8 Jan. 2020 II]
The first member of the Balmer series of hydrogen atom has a wavelength of 6561 Å. The wavelength of the second member of the Balmer series (in nm) is ______.
[NA 8 Jan. 2020 II]
Q.157 Correct
Q.157 In-correct
Q.157 Unattempt
The time period of revolution of electron in its ground state orbit in a hydrogen atom is 1.6×10−16s. The frequency of revolution of the electron in its first excited state ( in s−1) is:
[7 Jan. 2020 I]
The time period of revolution of electron in its ground state orbit in a hydrogen atom is 1.6×10−16s. The frequency of revolution of the electron in its first excited state ( in s−1) is:
[7 Jan. 2020 I]
Q.158 Correct
Q.158 In-correct
Q.158 Unattempt
The activity of a radioactive sample falls from 700 s‌−1 to 500 s‌−1 in 30 minutes. Its half life is close to:
[7 Jan. 2020, II]
The activity of a radioactive sample falls from 700 s‌−1 to 500 s‌−1 in 30 minutes. Its half life is close to:
[7 Jan. 2020, II]
Q.159 Correct
Q.159 In-correct
Q.159 Unattempt
A particle of mass 200MeV∕c2 collides with a hydrogen atom at rest. Soon after the collision the particle comes to rest, and the atom recoils and goes to its first excited state. The initial kinetic energy of the particle (in eV) is
N
4
. The value of N is :
(Given the mass of the hydrogen atom to be 1 GeV/c‌2)
[NA Sep. 05, 2020 (I)]
A particle of mass 200MeV∕c2 collides with a hydrogen atom at rest. Soon after the collision the particle comes to rest, and the atom recoils and goes to its first excited state. The initial kinetic energy of the particle (in eV) is
N
4
. The value of N is :
(Given the mass of the hydrogen atom to be 1 GeV/c‌2)
[NA Sep. 05, 2020 (I)]
Q.160 Correct
Q.160 In-correct
Q.160 Unattempt
In the line spectra of hydrogen atom, difference between the largest and the shortest wavelengths of the Lyman series is 304 Å. The corresponding difference for the Paschan series in Å is : _______.
[NA Sep. 04, 2020 (I)]
In the line spectra of hydrogen atom, difference between the largest and the shortest wavelengths of the Lyman series is 304 Å. The corresponding difference for the Paschan series in Å is : _______.
[NA Sep. 04, 2020 (I)]
Q.161 Correct
Q.161 In-correct
Q.161 Unattempt
In a hydrogen atom the electron makes a transition from (n +1)‌th level to the nth level. If n>>1, the frequency of radiation emitted is proportional to :
[Sep. 02, 2020 (II)]
In a hydrogen atom the electron makes a transition from (n +1)‌th level to the nth level. If n>>1, the frequency of radiation emitted is proportional to :
[Sep. 02, 2020 (II)]
Q.162 Correct
Q.162 In-correct
Q.162 Unattempt
The radius R of a nucleus of mass number A can be estimated by the formula R=(1.3×10−15)A1∕3m. It follows that the mass density of a nucleus is of the order of :
(Mprot. ≅Mneut. ≃1.67×10−27kg)
[Sep. 03, 2020 (II)]
The radius R of a nucleus of mass number A can be estimated by the formula R=(1.3×10−15)A1∕3m. It follows that the mass density of a nucleus is of the order of :
(Mprot. ≅Mneut. ≃1.67×10−27kg)
[Sep. 03, 2020 (II)]
Q.163 Correct
Q.163 In-correct
Q.163 Unattempt
You are given that mass of ‌37Li=7.0160u
Mass of ‌24He=4.0026u
and Mass of ‌11H=1.0079u
When 20g of ‌37Li is converted into ‌24He by proton capture, the energy liberated, (in kWh ), is :
[Mass of nucleon left.=1GeV∕c2]
[Sep. 06,2020 (I)]
You are given that mass of ‌37Li=7.0160u
Mass of ‌24He=4.0026u
and Mass of ‌11H=1.0079u
When 20g of ‌37Li is converted into ‌24He by proton capture, the energy liberated, (in kWh ), is :
[Mass of nucleon left.=1GeV∕c2]
[Sep. 06,2020 (I)]
Q.164 Correct
Q.164 In-correct
Q.164 Unattempt
Given the masses of various atomic particles mp=1.0072u mn=1.0087u,me=0.000548u,mv−=0,md=2.0141u, wherep‌equiv proton, n≡ neutron, e≡ electron, v≡ antineutrino and d≡ deuteron. Which of the following process is allowed by momentum and energy conservation?
[Sep. 06,2020 (II)]
Given the masses of various atomic particles mp=1.0072u mn=1.0087u,me=0.000548u,mv−=0,md=2.0141u, wherep‌equiv proton, n≡ neutron, e≡ electron, v≡ antineutrino and d≡ deuteron. Which of the following process is allowed by momentum and energy conservation?
[Sep. 06,2020 (II)]
Q.165 Correct
Q.165 In-correct
Q.165 Unattempt
Find the Binding energy per neucleon for ‌50120Sn. Mass of proton mp=1.00783U, mass of neutron mn=1.00867Uandmass of tin nucleus mSn=119.902199U.
(take‌1‌U=931MeV)
[Sep. 04,2020 (II)]
Find the Binding energy per neucleon for ‌50120Sn. Mass of proton mp=1.00783U, mass of neutron mn=1.00867Uandmass of tin nucleus mSn=119.902199U.
(take‌1‌U=931MeV)
[Sep. 04,2020 (II)]
Q.166 Correct
Q.166 In-correct
Q.166 Unattempt
In a reactor, 2kg of 92U235 fuel is fully used up in 30 days. The energy released per fission is 200MeV. Given that the Avogadro number, N=6.023×1026 per kilo mole and 1eV =1.6×10−19J. The power output of the reactor is close to:
[Sep. 02, 2020 (I)]
In a reactor, 2kg of 92U235 fuel is fully used up in 30 days. The energy released per fission is 200MeV. Given that the Avogadro number, N=6.023×1026 per kilo mole and 1eV =1.6×10−19J. The power output of the reactor is close to:
[Sep. 02, 2020 (I)]
Q.167 Correct
Q.167 In-correct
Q.167 Unattempt
Activities of three radioactive substances A,B and C are represented by the curves A,B and C, in the figure. Then their half-lives T
1
2
(A):T
1
2
(B):T
1
2
(C) are in the ratio:

[Sep. 05, 2020 (I)]
Activities of three radioactive substances A,B and C are represented by the curves A,B and C, in the figure. Then their half-lives T
1
2
(A):T
1
2
(B):T
1
2
(C) are in the ratio:

[Sep. 05, 2020 (I)]
Q.168 Correct
Q.168 In-correct
Q.168 Unattempt
A radioactive nucleus decays by two different processes. The half life for the first process is 10 s and that for the second is 100 s. The effective half life of the nucleus is close to :
[Sep. 05, 2020 (II)]
A radioactive nucleus decays by two different processes. The half life for the first process is 10 s and that for the second is 100 s. The effective half life of the nucleus is close to :
[Sep. 05, 2020 (II)]
Q.169 Correct
Q.169 In-correct
Q.169 Unattempt
In a radioactive material, fraction of active material remaining after time t is 9∕16. The fraction that was remaining after t∕2 is :
[Sep. 03, 2020 (I)]
In a radioactive material, fraction of active material remaining after time t is 9∕16. The fraction that was remaining after t∕2 is :
[Sep. 03, 2020 (I)]
Q.170 Correct
Q.170 In-correct
Q.170 Unattempt
In a hydrogen like atom, when an electron jumps from the M-shell to the L-shell, the wavelength of emitted radiation is l. If an electron jumps from N-shell to the L-shell, the wavelength of emitted radiation will be:
[11 Jan 2019 II]
In a hydrogen like atom, when an electron jumps from the M-shell to the L-shell, the wavelength of emitted radiation is l. If an electron jumps from N-shell to the L-shell, the wavelength of emitted radiation will be:
[11 Jan 2019 II]
Q.171 Correct
Q.171 In-correct
Q.171 Unattempt
Consider the nuclear fission
Ne20→He4+C12
Given that the binding energy/nucleon of Ne20,He4 and C12 are, respectively, 8.03MeV,7.07MeV and 7.86MeV identify the correct statement:
[10 Jan. 2019 II]
Consider the nuclear fission
Ne20→He4+C12
Given that the binding energy/nucleon of Ne20,He4 and C12 are, respectively, 8.03MeV,7.07MeV and 7.86MeV identify the correct statement:
[10 Jan. 2019 II]
Q.172 Correct
Q.172 In-correct
Q.172 Unattempt
In a radioactive decay chain, the initial nucleus is ‌90232‌Th.At the end there are 6α -particles and 4β -particles which are emitted. If the end nucleus is ‌ZAX,A and Z are given by :
[12 Jan. 2019, II]
In a radioactive decay chain, the initial nucleus is ‌90232‌Th.At the end there are 6α -particles and 4β -particles which are emitted. If the end nucleus is ‌ZAX,A and Z are given by :
[12 Jan. 2019, II]
Q.173 Correct
Q.173 In-correct
Q.173 Unattempt
Using a nuclear counter the count rate of emitted particles from a radioactive source is measured. At t =0 it was 1600 counts per second and t = 8 seconds it was 100 counts per second. The count rate observed,as counts per second, at t = 6 seconds is close to:
[10 Jan. 2019 I]
Using a nuclear counter the count rate of emitted particles from a radioactive source is measured. At t =0 it was 1600 counts per second and t = 8 seconds it was 100 counts per second. The count rate observed,as counts per second, at t = 6 seconds is close to:
[10 Jan. 2019 I]
Q.174 Correct
Q.174 In-correct
Q.174 Unattempt
A sample of radioactive material A, that has an activity of 10 mCi (1Ci=3.7×1010 decays/s), has twice the number of nuclei as another sample of a different radioactive material B which has an acitvity of 20 mCi. The correct choices for halflives of A and B would then be respectively:
[9 Jan. 2019 I]
A sample of radioactive material A, that has an activity of 10 mCi (1Ci=3.7×1010 decays/s), has twice the number of nuclei as another sample of a different radioactive material B which has an acitvity of 20 mCi. The correct choices for halflives of A and B would then be respectively:
[9 Jan. 2019 I]
Q.175 Correct
Q.175 In-correct
Q.175 Unattempt
At a given instant, say t=0, two radioactive substances A and B have equal activities. The ratio
RB
RA
 of their activities after time t itself decays with time t as e−3t. If the half-life of A is ln‌2, the half-life of B is:
[9 Jan. 2019 II]
At a given instant, say t=0, two radioactive substances A and B have equal activities. The ratio
RB
RA
 of their activities after time t itself decays with time t as e−3t. If the half-life of A is ln‌2, the half-life of B is:
[9 Jan. 2019 II]
Q.176 Correct
Q.176 In-correct
Q.176 Unattempt
An excited He+ ion emits two photons in succession, with wavelengths 108.5nm and 30.4nm, in making a transition to ground state. The quantum number n, corresponding to its initial excited state is (for photon of wavelength », energy E=
1240eV
λ( in nm )
[12 April 2019 II]
An excited He+ ion emits two photons in succession, with wavelengths 108.5nm and 30.4nm, in making a transition to ground state. The quantum number n, corresponding to its initial excited state is (for photon of wavelength », energy E=
1240eV
λ( in nm )
[12 April 2019 II]
Q.177 Correct
Q.177 In-correct
Q.177 Unattempt
The electron in a hydrogen atom first jumps from the third excited state to the second excited state and subsequently to the first excited state. The ratio of the respective wavelengths,
λ1
λ2
 , of the photons emitted in this process is :
[12 April 2019 II]
The electron in a hydrogen atom first jumps from the third excited state to the second excited state and subsequently to the first excited state. The ratio of the respective wavelengths,
λ1
λ2
 , of the photons emitted in this process is :
[12 April 2019 II]
Q.178 Correct
Q.178 In-correct
Q.178 Unattempt
Consider an electron in a hydrogen atom, revolving in its second excited state (having radius 4.65 Å). The de- Broglie wavelength of this electron is :
[12 April 2019 II]
Consider an electron in a hydrogen atom, revolving in its second excited state (having radius 4.65 Å). The de- Broglie wavelength of this electron is :
[12 April 2019 II]
Q.179 Correct
Q.179 In-correct
Q.179 Unattempt
In Li++, electron in first Bohr orbit is excited to a level by a radiation of wavelength lambda. When the ion gets deexcited to the ground state in all possible ways (including intermediate emissions), a total of six spectral lines are observed. What is the value of λ?
(Given : h=6.63×10−34Js; c=3×108ms−1)
[10 April 2019 II]
In Li++, electron in first Bohr orbit is excited to a level by a radiation of wavelength lambda. When the ion gets deexcited to the ground state in all possible ways (including intermediate emissions), a total of six spectral lines are observed. What is the value of λ?
(Given : h=6.63×10−34Js; c=3×108ms−1)
[10 April 2019 II]
Q.180 Correct
Q.180 In-correct
Q.180 Unattempt
Taking the wavelength of first Balmer line in hydrogen spectrum (n = 3 to n = 2) as 660 nm, the wavelength of the 2‌nd Balmer line (n = 4 to n = 2) will be;
[9 April 2019 I]
Taking the wavelength of first Balmer line in hydrogen spectrum (n = 3 to n = 2) as 660 nm, the wavelength of the 2‌nd Balmer line (n = 4 to n = 2) will be;
[9 April 2019 I]
Q.181 Correct
Q.181 In-correct
Q.181 Unattempt
A He‌+ ion is in its first excited state. Its ionization energy is:
[9 April 2019 II]
A He‌+ ion is in its first excited state. Its ionization energy is:
[9 April 2019 II]
Q.182 Correct
Q.182 In-correct
Q.182 Unattempt
Radiation coming from transitions n = 2 to n = 1 of hydrogen atoms fall on He‌+ ions in n = 1 and n = 2 states. The possible transition of helium ions as they absorb energy from the radiation is :
[8 April 2019 I]
Radiation coming from transitions n = 2 to n = 1 of hydrogen atoms fall on He‌+ ions in n = 1 and n = 2 states. The possible transition of helium ions as they absorb energy from the radiation is :
[8 April 2019 I]
Q.183 Correct
Q.183 In-correct
Q.183 Unattempt
A hydrogen atom, initially in the ground state is excited by absorbing a photon of wavelength 980Å. The radius of the atom in the excited state, in terms of Bohr radius a0 ,will be:
[11 April 2019 I]
A hydrogen atom, initially in the ground state is excited by absorbing a photon of wavelength 980Å. The radius of the atom in the excited state, in terms of Bohr radius a0 ,will be:
[11 April 2019 I]
Q.184 Correct
Q.184 In-correct
Q.184 Unattempt
The ratio of the mass densities of nuclei of ‌40Ca and ‌16O is close to :
[8 April 2019 II]
The ratio of the mass densities of nuclei of ‌40Ca and ‌16O is close to :
[8 April 2019 II]
Q.185 Correct
Q.185 In-correct
Q.185 Unattempt
Two radioactive materials A and B have decay constants 10λ and λ, respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of A to that of B will be 1∕e after a time :
[10 April 2019, I]
Two radioactive materials A and B have decay constants 10λ and λ, respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of A to that of B will be 1∕e after a time :
[10 April 2019, I]
Q.186 Correct
Q.186 In-correct
Q.186 Unattempt
Two radioactive substances A and B have decay constants 5‌lambda and λ respectively. At t=0, a sample has the same number of the two nuclei. The time taken for the ratio of the number of nuclei to become (
1
e
)2 will be
[10 April 2019, II]
Two radioactive substances A and B have decay constants 5‌lambda and λ respectively. At t=0, a sample has the same number of the two nuclei. The time taken for the ratio of the number of nuclei to become (
1
e
)2 will be
[10 April 2019, II]
Q.187 Correct
Q.187 In-correct
Q.187 Unattempt
An electron from various excited states of hydrogen atom emit radiation to come to the ground state. Let λn,λg be the de Broglie wavelength of the electron in the nth state and the ground state respectively. Let Λn be the wavelength of the emitted photon in the transition from the nth state to the ground state. For large n,(A,B are constants)
[2018]
An electron from various excited states of hydrogen atom emit radiation to come to the ground state. Let λn,λg be the de Broglie wavelength of the electron in the nth state and the ground state respectively. Let Λn be the wavelength of the emitted photon in the transition from the nth state to the ground state. For large n,(A,B are constants)
[2018]
Q.188 Correct
Q.188 In-correct
Q.188 Unattempt
If the series limit frequency of the Lyman series is v1 , then the series limit frequency of the P-fund series is
[2018]
If the series limit frequency of the Lyman series is v1 , then the series limit frequency of the P-fund series is
[2018]
Q.189 Correct
Q.189 In-correct
Q.189 Unattempt
The de-Broglie wavelength (λB) associated with the electron orbiting in the second excited state of hydrogen atom is related to that in the ground state (λG) by
[Online April 16, 2018]
The de-Broglie wavelength (λB) associated with the electron orbiting in the second excited state of hydrogen atom is related to that in the ground state (λG) by
[Online April 16, 2018]
Q.190 Correct
Q.190 In-correct
Q.190 Unattempt
The energy required to remove the electron from a singly ionized Helium atom is 2.2 times the energy required to remove an electron from Helium atom. The total energy required to ionize the Helium atom completely is:
[Online April 15, 2018]
The energy required to remove the electron from a singly ionized Helium atom is 2.2 times the energy required to remove an electron from Helium atom. The total energy required to ionize the Helium atom completely is:
[Online April 15, 2018]
Q.191 Correct
Q.191 In-correct
Q.191 Unattempt
Muon (µ−1) is negatively charged (|q|=|e|) with a mass mµ=200me, where me is the mass of the electron and e is the electronic charge. If µ−1 is bound to a proton to form a hydrogen like atom, identify the correct statements
(A) Radius of the muonic orbit is 200 times smaller than that of the electron
(B) the speed of the µ−1 in the nth orbit is
1
200
 times that of the election in the nth orbit
(C) The lonization energy of muonic atom is 200 times more than that of an hydrogen atom
(D) The momentum of the muon in the nth orbit is 200 times more than that of the electron
[Online April 15, 2018]
Muon (µ−1) is negatively charged (|q|=|e|) with a mass mµ=200me, where me is the mass of the electron and e is the electronic charge. If µ−1 is bound to a proton to form a hydrogen like atom, identify the correct statements
(A) Radius of the muonic orbit is 200 times smaller than that of the electron
(B) the speed of the µ−1 in the nth orbit is
1
200
 times that of the election in the nth orbit
(C) The lonization energy of muonic atom is 200 times more than that of an hydrogen atom
(D) The momentum of the muon in the nth orbit is 200 times more than that of the electron
[Online April 15, 2018]
Q.192 Correct
Q.192 In-correct
Q.192 Unattempt
An unstable heavy nucleus at rest breaks into two nuclei which move away with velocities in the ratio of 8:27. The ratio of the radii of the nuclei (assumed to be spherical ) is:
[Online April 15, 2018]
An unstable heavy nucleus at rest breaks into two nuclei which move away with velocities in the ratio of 8:27. The ratio of the radii of the nuclei (assumed to be spherical ) is:
[Online April 15, 2018]
Q.193 Correct
Q.193 In-correct
Q.193 Unattempt
At some instant, a radioactive sample S1 having an activity 5µCi has twice the number of nuclei as another sample S2 which has an activity of 10µCi. The half lives of S1 and S2 are
[Online April 16, 2018]
At some instant, a radioactive sample S1 having an activity 5µCi has twice the number of nuclei as another sample S2 which has an activity of 10µCi. The half lives of S1 and S2 are
[Online April 16, 2018]
Q.194 Correct
Q.194 In-correct
Q.194 Unattempt
A solution containing active cobalt ‌2760 Co having activity of 0.8µCi and decay constant λ is injected in an animal's body. If 1cm3 of blood is drawn from the animal's body after 10 hrs of injection, the activity found was 300 decays per minute. What is the volume of blood that is flowing in the body? (1Ci=3.7×1010 decay per second and at t =10hrs‌ ‌e−λt=0.84)
[Online April 15, 2018]
A solution containing active cobalt ‌2760 Co having activity of 0.8µCi and decay constant λ is injected in an animal's body. If 1cm3 of blood is drawn from the animal's body after 10 hrs of injection, the activity found was 300 decays per minute. What is the volume of blood that is flowing in the body? (1Ci=3.7×1010 decay per second and at t =10hrs‌ ‌e−λt=0.84)
[Online April 15, 2018]
Q.195 Correct
Q.195 In-correct
Q.195 Unattempt
Some energy levels of a molecule are shown in the figure.
The ratio of the wavelengths r=λ1∕λ2, is given by

[2017]
Some energy levels of a molecule are shown in the figure.
The ratio of the wavelengths r=λ1∕λ2, is given by

[2017]
Q.196 Correct
Q.196 In-correct
Q.196 Unattempt
The acceleration of an electron in the first orbit of the hydrogen atom (z = 1) is :
[Online April 9, 2017]
The acceleration of an electron in the first orbit of the hydrogen atom (z = 1) is :
[Online April 9, 2017]
Q.197 Correct
Q.197 In-correct
Q.197 Unattempt
According to Bohr's theory, the time averaged magnetic field at the centre (i.e. nucleus) of a hydrogen atom due to the motion of electrons in the nth orbit is proportional to :
(n= principal quantum number )
[Online April 8, 2017]
According to Bohr's theory, the time averaged magnetic field at the centre (i.e. nucleus) of a hydrogen atom due to the motion of electrons in the nth orbit is proportional to :
(n= principal quantum number )
[Online April 8, 2017]
Q.198 Correct
Q.198 In-correct
Q.198 Unattempt
Imagine that a reactor converts all given mass into energy and that it operates at a power level of 109 watt. The mass of the fuel consumed per hour in the reactor will be :
(velocity of light, c is 3×108m∕s )
[Online April 9, 2017]
Imagine that a reactor converts all given mass into energy and that it operates at a power level of 109 watt. The mass of the fuel consumed per hour in the reactor will be :
(velocity of light, c is 3×108m∕s )
[Online April 9, 2017]
Q.199 Correct
Q.199 In-correct
Q.199 Unattempt
Two deuterons undergo nuclear fusion to form a Helium nucleus. Energy released in this process is : (given binding energy per nucleon for deuteron=1.1 MeV and for helium=7.0 MeV)
[Online April 8, 2017]
Two deuterons undergo nuclear fusion to form a Helium nucleus. Energy released in this process is : (given binding energy per nucleon for deuteron=1.1 MeV and for helium=7.0 MeV)
[Online April 8, 2017]
Q.200 Correct
Q.200 In-correct
Q.200 Unattempt
A radioactive nucleus A with a half life T, decays into a nucleus B. At t=0, there is no nucleus B. At sometime, the ratio of the number of B to that of A is 0.3. Then, t is given by
[2017]
A radioactive nucleus A with a half life T, decays into a nucleus B. At t=0, there is no nucleus B. At sometime, the ratio of the number of B to that of A is 0.3. Then, t is given by
[2017]
Q.201 Correct
Q.201 In-correct
Q.201 Unattempt
A hydrogen atom makes a transition from n = 2 to n = 1 and emits a photon. This photon strikes a doubly ionized lithium atom (z = 3) in excited state and completely removes the orbiting electron. The least quantum number for the excited state of the ion for the process is :
[Online April 9, 2016]
A hydrogen atom makes a transition from n = 2 to n = 1 and emits a photon. This photon strikes a doubly ionized lithium atom (z = 3) in excited state and completely removes the orbiting electron. The least quantum number for the excited state of the ion for the process is :
[Online April 9, 2016]
Q.202 Correct
Q.202 In-correct
Q.202 Unattempt
Half-lives of two radioactive elements A and B are 20 minutes and 40 minutes, respectively. Initially, the samples have equal number of nuclei. After 80 minutes, the ratio of decayed number of A and B nuclei will be :
[2016]
Half-lives of two radioactive elements A and B are 20 minutes and 40 minutes, respectively. Initially, the samples have equal number of nuclei. After 80 minutes, the ratio of decayed number of A and B nuclei will be :
[2016]
Q.203 Correct
Q.203 In-correct
Q.203 Unattempt
As an electron makes a transition from an excited state to the ground state of a hydrogen - like atom/ion :
[2015]
As an electron makes a transition from an excited state to the ground state of a hydrogen - like atom/ion :
[2015]
Q.204 Correct
Q.204 In-correct
Q.204 Unattempt
The de–Broglie wavelength associated with the electron in the n = 4 level is :
[Online April 11, 2015]
The de–Broglie wavelength associated with the electron in the n = 4 level is :
[Online April 11, 2015]
Q.205 Correct
Q.205 In-correct
Q.205 Unattempt
If one were to apply Bohr model to a particle of mass ‘m’ and charge ‘q’ moving in a plane under the influence of a magnetic field ‘B’, the energy of the charged particle in the nth level will be :
[Online April 10, 2015]
If one were to apply Bohr model to a particle of mass ‘m’ and charge ‘q’ moving in a plane under the influence of a magnetic field ‘B’, the energy of the charged particle in the nth level will be :
[Online April 10, 2015]
Q.206 Correct
Q.206 In-correct
Q.206 Unattempt
Let Nβ be the number of β particles emitted by 1 gram of Na24 radioactive nuclei (half life =15hrs ) in 7.5 hours, Nβ is close to (Avogadro number =6.023×1023∕g. mole )
[Online April 11, 2015]
Let Nβ be the number of β particles emitted by 1 gram of Na24 radioactive nuclei (half life =15hrs ) in 7.5 hours, Nβ is close to (Avogadro number =6.023×1023∕g. mole )
[Online April 11, 2015]
Q.207 Correct
Q.207 In-correct
Q.207 Unattempt
The radiation corresponding to 3→2 transition of hydrogen atom falls on a metal surface to produce photoelectrons. These electrons are made to enter a magnetic field of 3×10−4T. If the radius of the largest circular path followed by these electrons is 10.0mm, the work function of the metal is close to:
[2014]
The radiation corresponding to 3→2 transition of hydrogen atom falls on a metal surface to produce photoelectrons. These electrons are made to enter a magnetic field of 3×10−4T. If the radius of the largest circular path followed by these electrons is 10.0mm, the work function of the metal is close to:
[2014]
Q.208 Correct
Q.208 In-correct
Q.208 Unattempt
Hydrogen (‌1H1), Deuterium (‌1H2), singly ionised Helium(‌2He4)+ and doubly ionised lithium (‌3Li6)++ all have one electron around the nucleus. Consider an electron transition from n=2 to n=1. If the wavelengths of emitted radiation are λ1,λ2,λ3 and λ4 respectively then approximately which one of the following is correct?
[2014]
Hydrogen (‌1H1), Deuterium (‌1H2), singly ionised Helium(‌2He4)+ and doubly ionised lithium (‌3Li6)++ all have one electron around the nucleus. Consider an electron transition from n=2 to n=1. If the wavelengths of emitted radiation are λ1,λ2,λ3 and λ4 respectively then approximately which one of the following is correct?
[2014]
Q.209 Correct
Q.209 In-correct
Q.209 Unattempt
Match List - I (Experiment performed) with List-II (Phenomena discovered/associated) and select the correct option from the options given below the lists:

[Online April 19, 2014]
Match List - I (Experiment performed) with List-II (Phenomena discovered/associated) and select the correct option from the options given below the lists:

[Online April 19, 2014]
Q.210 Correct
Q.210 In-correct
Q.210 Unattempt
The binding energy of the electron in a hydrogen atom is 13.6 eV, the energy required to remove the electron from the first excited state of Li‌++ is:
[Online April 9, 2014]
The binding energy of the electron in a hydrogen atom is 13.6 eV, the energy required to remove the electron from the first excited state of Li‌++ is:
[Online April 9, 2014]
Q.211 Correct
Q.211 In-correct
Q.211 Unattempt
A piece of wood from a recently cut tree shows 20 decays per minute. A wooden piece of same size placed in a museum (obtained from a tree cut many years back) shows 2 decays per minute. If half life of C14 is 5730 years, then age of the wooden piece placed in the museum is approximately:
[Online April 19, 2014]
A piece of wood from a recently cut tree shows 20 decays per minute. A wooden piece of same size placed in a museum (obtained from a tree cut many years back) shows 2 decays per minute. If half life of C14 is 5730 years, then age of the wooden piece placed in the museum is approximately:
[Online April 19, 2014]
Q.212 Correct
Q.212 In-correct
Q.212 Unattempt
A piece of bone of an animal from a ruin is found to have ‌14C activity of 12 disintegrations per minute per gm of its carbon content. The ‌14C activity of a living animal is 16 disintegrations per minute per gm. How long ago nearly did the animal die? (Given half life of ‌14C is t1∕2=5760 years)
[Online April 12, 2014]
A piece of bone of an animal from a ruin is found to have ‌14C activity of 12 disintegrations per minute per gm of its carbon content. The ‌14C activity of a living animal is 16 disintegrations per minute per gm. How long ago nearly did the animal die? (Given half life of ‌14C is t1∕2=5760 years)
[Online April 12, 2014]
Q.213 Correct
Q.213 In-correct
Q.213 Unattempt
A radioactive nuclei with decay constant
0.5
s
 is being produced at a constant rate of 100 nuclei/s. If at t=0 there were no nuclei, the time when there are 50 nuclei is:
[Online April 11, 2014]
A radioactive nuclei with decay constant
0.5
s
 is being produced at a constant rate of 100 nuclei/s. If at t=0 there were no nuclei, the time when there are 50 nuclei is:
[Online April 11, 2014]
Q.214 Correct
Q.214 In-correct
Q.214 Unattempt
Ina hydrogen like atom electron make transition from an energy level with quantum number n to another with quantum number (n−1). If n>>1, the frequency of radiation emitted is proportional to :
[2013]
Ina hydrogen like atom electron make transition from an energy level with quantum number n to another with quantum number (n−1). If n>>1, the frequency of radiation emitted is proportional to :
[2013]
Q.215 Correct
Q.215 In-correct
Q.215 Unattempt
A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. It will emit :
[Online April 25, 2013]
A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. It will emit :
[Online April 25, 2013]
Q.216 Correct
Q.216 In-correct
Q.216 Unattempt
In the Bohr's model of hydrogen-like atom the force between the nucleus and the electron is modified asF=
e2
4πε0
(
1
r2
+
β
r3
), where β is a constant. For this atom, the radius of the nth orbit in terms of the Bohr radius (a0=
ε0h2
mπe2
) is:
[Online April 23, 2013]
In the Bohr's model of hydrogen-like atom the force between the nucleus and the electron is modified asF=
e2
4πε0
(
1
r2
+
β
r3
), where β is a constant. For this atom, the radius of the nth orbit in terms of the Bohr radius (a0=
ε0h2
mπe2
) is:
[Online April 23, 2013]
Q.217 Correct
Q.217 In-correct
Q.217 Unattempt
Orbits of a particle moving in a circle are such that the perimeter of the orbit equals an integer number of deBroglie wavelengths of the particle. For a charged particle moving in a plane perpendicular to a magnetic field, the radius of the nth orbital will therefore be proportional to :
[Online April 22, 2013]
Orbits of a particle moving in a circle are such that the perimeter of the orbit equals an integer number of deBroglie wavelengths of the particle. For a charged particle moving in a plane perpendicular to a magnetic field, the radius of the nth orbital will therefore be proportional to :
[Online April 22, 2013]
Q.218 Correct
Q.218 In-correct
Q.218 Unattempt
In the Bohr model an electron moves in a circular orbit around the proton. Considering the orbiting electron to be a circular current loop, the magnetic moment of the hydrogen atom, when the electron is in nth excited state, is :
[Online April 9, 2013]
In the Bohr model an electron moves in a circular orbit around the proton. Considering the orbiting electron to be a circular current loop, the magnetic moment of the hydrogen atom, when the electron is in nth excited state, is :
[Online April 9, 2013]
Q.219 Correct
Q.219 In-correct
Q.219 Unattempt
When Uranium is bombarded with neutrons, it undergoes fission. The fission reaction can be written as :
92U235+‌0n1→‌56Ba141+‌36Kr92 +3x+Q (energy)
where three particles named x are produced and energy Q is released. What is the name of the particle x ?
[Online April 9, 2013]
When Uranium is bombarded with neutrons, it undergoes fission. The fission reaction can be written as :
92U235+‌0n1→‌56Ba141+‌36Kr92 +3x+Q (energy)
where three particles named x are produced and energy Q is released. What is the name of the particle x ?
[Online April 9, 2013]
Q.220 Correct
Q.220 In-correct
Q.220 Unattempt
The half-life of a radioactive element A is the same as the mean-life of another radioactive element B. Initially both substances have the same number of atoms, then :
[Online April 22, 2013]
The half-life of a radioactive element A is the same as the mean-life of another radioactive element B. Initially both substances have the same number of atoms, then :
[Online April 22, 2013]
Q.221 Correct
Q.221 In-correct
Q.221 Unattempt
In the Rutherford experiment, a-particles are scattered from a nucleus as shown. Out of the four paths, which path is not possible?

[Online May 7, 2012]
In the Rutherford experiment, a-particles are scattered from a nucleus as shown. Out of the four paths, which path is not possible?

[Online May 7, 2012]
Q.222 Correct
Q.222 In-correct
Q.222 Unattempt
Hydrogen atom is excited from ground state to another state with principal quantum number equal to 4. Then the number of spectral lines in the emission spectra will be :
[2012]
Hydrogen atom is excited from ground state to another state with principal quantum number equal to 4. Then the number of spectral lines in the emission spectra will be :
[2012]
Q.223 Correct
Q.223 In-correct
Q.223 Unattempt
A diatomic molecule is made of two masses m1 and m2 which are separated by a distance r. If we calculate its rotational energy by applying Bohr's rule of angular momentum quantization, its energy will be given by: (n is an integer)
[2012]
A diatomic molecule is made of two masses m1 and m2 which are separated by a distance r. If we calculate its rotational energy by applying Bohr's rule of angular momentum quantization, its energy will be given by: (n is an integer)
[2012]
Q.224 Correct
Q.224 In-correct
Q.224 Unattempt
Which of the plots shown in the figure represents speed (vn) of the electron in a hydrogen atom as a function of the principal quantum number (n)?

[Online May 26, 2012]
Which of the plots shown in the figure represents speed (vn) of the electron in a hydrogen atom as a function of the principal quantum number (n)?

[Online May 26, 2012]
Q.225 Correct
Q.225 In-correct
Q.225 Unattempt
A doubly ionised Li atom is excited from its ground state (n=1) to n=3 state. The wavelengths of the spectral lines are given by λ32,λ31 and λ21. The ratio λ32∕λ31 and λ21∕λ31 are, respectively
[Online May 12,2012]
A doubly ionised Li atom is excited from its ground state (n=1) to n=3 state. The wavelengths of the spectral lines are given by λ32,λ31 and λ21. The ratio λ32∕λ31 and λ21∕λ31 are, respectively
[Online May 12,2012]
Q.226 Correct
Q.226 In-correct
Q.226 Unattempt
A hypothetical atom has only three energy levels. The ground level has energy, E1=−8eV. The two excited states have energies, E2=−6eV and E3=−2eV. Then which of the following wavelengths will not be present in the emission spectrum of this atom?
[Online May 12,2012]
A hypothetical atom has only three energy levels. The ground level has energy, E1=−8eV. The two excited states have energies, E2=−6eV and E3=−2eV. Then which of the following wavelengths will not be present in the emission spectrum of this atom?
[Online May 12,2012]
Q.227 Correct
Q.227 In-correct
Q.227 Unattempt
The electron of a hydrogen atom makes a transition from the (n+1)th orbit to the nth orbit. For large n the wavelength of the emitted radiation is proportional to
[Online May 7,2012]
The electron of a hydrogen atom makes a transition from the (n+1)th orbit to the nth orbit. For large n the wavelength of the emitted radiation is proportional to
[Online May 7,2012]
Q.228 Correct
Q.228 In-correct
Q.228 Unattempt
Assume that a neutron breaks into a proton and an electron. The energy released during this process is : (mass of neutron =1.6725×10−27kg, mass of proton =1.6725× 10−27kg, mass of electron =9×10−31kg)
[2012]
Assume that a neutron breaks into a proton and an electron. The energy released during this process is : (mass of neutron =1.6725×10−27kg, mass of proton =1.6725× 10−27kg, mass of electron =9×10−31kg)
[2012]
Q.229 Correct
Q.229 In-correct
Q.229 Unattempt
Ionisation energy of Li (Lithium) atom in ground state is 5.4 eV. Binding energy of an electron in Li‌+ ion in ground state is 75.6 eV. Energy required to remove all three electrons of Lithium (Li) atom is
[Online May 19, 2012]
Ionisation energy of Li (Lithium) atom in ground state is 5.4 eV. Binding energy of an electron in Li‌+ ion in ground state is 75.6 eV. Energy required to remove all three electrons of Lithium (Li) atom is
[Online May 19, 2012]
Q.230 Correct
Q.230 In-correct
Q.230 Unattempt
The counting rate observed from a radioactive source at t = 0 was 1600 counts s‌−1, and t = 8 s, it was 100 counts s‌−1. The counting rate observed as counts s‌−1 at t = 6 s will be
[Online May 26, 2012]
The counting rate observed from a radioactive source at t = 0 was 1600 counts s‌−1, and t = 8 s, it was 100 counts s‌−1. The counting rate observed as counts s‌−1 at t = 6 s will be
[Online May 26, 2012]
Q.231 Correct
Q.231 In-correct
Q.231 Unattempt
The decay constants of a radioactive substance for α and β emission are λα and λβ respectively. If the substance emits α and β simultaneously, then the average half life of the material will be
[Online May 19, 2012]
The decay constants of a radioactive substance for α and β emission are λα and λβ respectively. If the substance emits α and β simultaneously, then the average half life of the material will be
[Online May 19, 2012]
Q.232 Correct
Q.232 In-correct
Q.232 Unattempt
Which of the following Statements is correct?
[Online May 12, 2012]
Which of the following Statements is correct?
[Online May 12, 2012]
Q.233 Correct
Q.233 In-correct
Q.233 Unattempt
A sample originally contained 1020 radioactive atoms, which emit α -particles. The ratio of α -particles emitted in the third year to that emitted during the second year is 0.3. How many α -particles were emitted in the first year?
[Online May 7, 2012]
A sample originally contained 1020 radioactive atoms, which emit α -particles. The ratio of α -particles emitted in the third year to that emitted during the second year is 0.3. How many α -particles were emitted in the first year?
[Online May 7, 2012]
Q.234 Correct
Q.234 In-correct
Q.234 Unattempt
Energy required for the electron excitation in Li‌++ from the first to the third Bohr orbit is :
[2011]
Energy required for the electron excitation in Li‌++ from the first to the third Bohr orbit is :
[2011]
Q.235 Correct
Q.235 In-correct
Q.235 Unattempt
After absorbing a slowly moving neutron of mass mN (momentum ≈0 ) a nucleus of mass M breaks into two nuclei of masses m1 and 5m1(6m1=M+mN) respectively. If the de Broglie wavelength of the nucleus with mass m1 is λ, the de Broglie wavelength of the nucleus will be
[2011]
After absorbing a slowly moving neutron of mass mN (momentum ≈0 ) a nucleus of mass M breaks into two nuclei of masses m1 and 5m1(6m1=M+mN) respectively. If the de Broglie wavelength of the nucleus with mass m1 is λ, the de Broglie wavelength of the nucleus will be
[2011]
Q.236 Correct
Q.236 In-correct
Q.236 Unattempt
The half life of a radioactive substance is 20 minutes. The approximate time interval (t2−t1) between the time t2 when
2
3
 of it had decayed and time t1 when
1
3
 of it had decayed is :
[2011]
The half life of a radioactive substance is 20 minutes. The approximate time interval (t2−t1) between the time t2 when
2
3
 of it had decayed and time t1 when
1
3
 of it had decayed is :
[2011]
Q.237 Correct
Q.237 In-correct
Q.237 Unattempt
Statement - 1 : A nucleus having energy E1 decays by β− emission to daughter nucleus having energy E2, but the β− rays are emitted with a continuous energy spectrum having end point energy E1−E2.
Statement - 2 : To conserve energy and momentum in β− decay at least three particles must take part in the transformation.
[2011 RS]
Statement - 1 : A nucleus having energy E1 decays by β− emission to daughter nucleus having energy E2, but the β− rays are emitted with a continuous energy spectrum having end point energy E1−E2.
Statement - 2 : To conserve energy and momentum in β− decay at least three particles must take part in the transformation.
[2011 RS]
Q.238 Correct
Q.238 In-correct
Q.238 Unattempt
The binding energy per nucleon for the parent nucleus is E1 and that for the daughter nuclei is E2. Then
[2010]
The binding energy per nucleon for the parent nucleus is E1 and that for the daughter nuclei is E2. Then
[2010]
Q.239 Correct
Q.239 In-correct
Q.239 Unattempt
The speed of daughter nuclei is
[2010]
The speed of daughter nuclei is
[2010]
Q.240 Correct
Q.240 In-correct
Q.240 Unattempt
A radioactive nucleus (initial mass number A and atomic number Z emits 3α - particles and 2 positrons. The ratio of number of neutrons to that of protons in the final nucleus will be
[2010]
A radioactive nucleus (initial mass number A and atomic number Z emits 3α - particles and 2 positrons. The ratio of number of neutrons to that of protons in the final nucleus will be
[2010]
Q.241 Correct
Q.241 In-correct
Q.241 Unattempt
The transition from the state n = 4 to n = 3 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from :
[2009]
The transition from the state n = 4 to n = 3 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from :
[2009]
Q.242 Correct
Q.242 In-correct
Q.242 Unattempt
Suppose an electron is attracted towards the origin by a force
k
r
 where ′k ' is a constant and ' r ' is the distance of the electron from the origin. By applying Bohr model to this system, the radius of the nth orbital of the electron is found to be ' rn ' and the kinetic energy of the electron to be ′T′n. Then which of the following is true?
[2008]
Suppose an electron is attracted towards the origin by a force
k
r
 where ′k ' is a constant and ' r ' is the distance of the electron from the origin. By applying Bohr model to this system, the radius of the nth orbital of the electron is found to be ' rn ' and the kinetic energy of the electron to be ′T′n. Then which of the following is true?
[2008]
Q.243 Correct
Q.243 In-correct
Q.243 Unattempt
Statement-1: Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion and
Statement-2 : For heavy nuclei, binding energy per nucleon increases with increasing Z while for light nuclei it decreases with increasing Z.
[2008]
Statement-1: Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion and
Statement-2 : For heavy nuclei, binding energy per nucleon increases with increasing Z while for light nuclei it decreases with increasing Z.
[2008]
Q.244 Correct
Q.244 In-correct
Q.244 Unattempt
Which of the following transitions in hydrogen atoms emit photons of highest frequency?
[2007]
Which of the following transitions in hydrogen atoms emit photons of highest frequency?
[2007]
Q.245 Correct
Q.245 In-correct
Q.245 Unattempt
Which of the following are the constituents of the nucleus?
[2007]
Which of the following are the constituents of the nucleus?
[2007]
Q.246 Correct
Q.246 In-correct
Q.246 Unattempt
If MO is the mass of an oxygen isotope 8O17,MP and MN are the masses of a proton and a neutron respectively, the nuclear binding energy of the isotope is
[2007]
If MO is the mass of an oxygen isotope 8O17,MP and MN are the masses of a proton and a neutron respectively, the nuclear binding energy of the isotope is
[2007]
Q.247 Correct
Q.247 In-correct
Q.247 Unattempt
The half-life period of a radio-active element X is same as the mean life time of another radio-active element Y. Initially they have the same number of atoms. Then
[2007]
The half-life period of a radio-active element X is same as the mean life time of another radio-active element Y. Initially they have the same number of atoms. Then
[2007]
Q.248 Correct
Q.248 In-correct
Q.248 Unattempt
An alpha nucleus of energy
1
2
mv2 bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to
[2006]
An alpha nucleus of energy
1
2
mv2 bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to
[2006]
Q.249 Correct
Q.249 In-correct
Q.249 Unattempt
When 3Li7 nuclei are bombarded by protons, and the resultant nuclei are 4Be8 , the emitted particles will be
[2006]
When 3Li7 nuclei are bombarded by protons, and the resultant nuclei are 4Be8 , the emitted particles will be
[2006]
Q.250 Correct
Q.250 In-correct
Q.250 Unattempt
If the binding energy per nucleon in ‌37Li and ‌24 He nuclei are 5.60MeV and 7.06MeV respectively, then in the reaction
p+‌37Li→2‌24He
energy of proton must be
[2006]
If the binding energy per nucleon in ‌37Li and ‌24 He nuclei are 5.60MeV and 7.06MeV respectively, then in the reaction
p+‌37Li→2‌24He
energy of proton must be
[2006]
Q.251 Correct
Q.251 In-correct
Q.251 Unattempt
The energy spectrum of β-particles [number N(E) as a function of β-energy E] emitted from a radioactive source is
[2006]
The energy spectrum of β-particles [number N(E) as a function of β-energy E] emitted from a radioactive source is
[2006]
Q.252 Correct
Q.252 In-correct
Q.252 Unattempt
The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy?

[2005]
The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy?

[2005]
Q.253 Correct
Q.253 In-correct
Q.253 Unattempt
If radius of the ‌1327 Al nucleus is estimated to be 3.6 fermi then the radius of ‌52125 Te nucleus be nearly
[2005]
If radius of the ‌1327 Al nucleus is estimated to be 3.6 fermi then the radius of ‌52125 Te nucleus be nearly
[2005]
Q.254 Correct
Q.254 In-correct
Q.254 Unattempt
A nuclear transformation is denoted by X(n,α)‌37Li Which of the following is the nucleus of element X?
[2005]
A nuclear transformation is denoted by X(n,α)‌37Li Which of the following is the nucleus of element X?
[2005]
Q.255 Correct
Q.255 In-correct
Q.255 Unattempt
Starting with a sample of pure ‌66Cu,
7
8
 of it decays into Zn in 15 minutes. The corresponding half life is
[2005]
Starting with a sample of pure ‌66Cu,
7
8
 of it decays into Zn in 15 minutes. The corresponding half life is
[2005]
Q.256 Correct
Q.256 In-correct
Q.256 Unattempt
The intensity of gamma radiation from a given source is I. On passing through 36mm of lead, it is reduced to
I
8
. The thickness of lead which will reduce the intensity to
I
2
 will be
[2005]
The intensity of gamma radiation from a given source is I. On passing through 36mm of lead, it is reduced to
I
8
. The thickness of lead which will reduce the intensity to
I
2
 will be
[2005]
Q.257 Correct
Q.257 In-correct
Q.257 Unattempt
An alpha -particle of energy 5MeV is scattered through 180° by a fixed uranium nucleus. The distance of closest approach is of the order of
[2004]
An alpha -particle of energy 5MeV is scattered through 180° by a fixed uranium nucleus. The distance of closest approach is of the order of
[2004]
Q.258 Correct
Q.258 In-correct
Q.258 Unattempt
A nucleus disintegrated into two nuclear parts which have their velocities in the ratio of 2 : 1. The ratio of their nuclear sizes will be
[2004]
A nucleus disintegrated into two nuclear parts which have their velocities in the ratio of 2 : 1. The ratio of their nuclear sizes will be
[2004]
Q.259 Correct
Q.259 In-correct
Q.259 Unattempt
The binding energy per nucleon of deuteron (‌12H) and helium nucleus (‌24He) is 1.1MeV and 7MeV respectively. If two deuteron nuclei react to form a single helium nucleus, then the energy released is
[2004]
The binding energy per nucleon of deuteron (‌12H) and helium nucleus (‌24He) is 1.1MeV and 7MeV respectively. If two deuteron nuclei react to form a single helium nucleus, then the energy released is
[2004]
Q.260 Correct
Q.260 In-correct
Q.260 Unattempt
The wavelengths involved in the spectrum of deuterium (12D) are slightly different from that of hydrogen spectrum, because
[2003]
The wavelengths involved in the spectrum of deuterium (12D) are slightly different from that of hydrogen spectrum, because
[2003]
Q.261 Correct
Q.261 In-correct
Q.261 Unattempt
When a U238 nucleus originally at rest, decays by emitting an alpha particle having a speed ' u ', the recoil speed of the residual nucleus is
[2003]
When a U238 nucleus originally at rest, decays by emitting an alpha particle having a speed ' u ', the recoil speed of the residual nucleus is
[2003]
Q.262 Correct
Q.262 In-correct
Q.262 Unattempt
In the nuclear fusion reaction
‌12H+‌13H→‌24He+n
given that the repulsive potential energy between the two nuclei is ∼7.7×10−14J, the temperature at which the gases must be heated to initiate the reaction is nearly [Boltzmann's Constant k=1.38×10−23J∕K]
[2003]
In the nuclear fusion reaction
‌12H+‌13H→‌24He+n
given that the repulsive potential energy between the two nuclei is ∼7.7×10−14J, the temperature at which the gases must be heated to initiate the reaction is nearly [Boltzmann's Constant k=1.38×10−23J∕K]
[2003]
Q.263 Correct
Q.263 In-correct
Q.263 Unattempt
Which of the following cannot be emitted by radioactive substances during their decay?
[2003]
Which of the following cannot be emitted by radioactive substances during their decay?
[2003]
Q.264 Correct
Q.264 In-correct
Q.264 Unattempt
A nucleus with Z=92 emits the following in a sequence:
α,β−,β−α,α,α,α,α,β−,β−, α,β+,β+,α
Then Z of the resulting nucleus is
[2003]
A nucleus with Z=92 emits the following in a sequence:
α,β−,β−α,α,α,α,α,β−,β−, α,β+,β+,α
Then Z of the resulting nucleus is
[2003]
Q.265 Correct
Q.265 In-correct
Q.265 Unattempt
A radioactive sample at any instant has its disintegration rate 5000 disintegrations per minute. After 5 minutes, the rate is 1250 disintegrations per minute. Then, the decay constant (per minute) is
[2003]
A radioactive sample at any instant has its disintegration rate 5000 disintegrations per minute. After 5 minutes, the rate is 1250 disintegrations per minute. Then, the decay constant (per minute) is
[2003]
Q.266 Correct
Q.266 In-correct
Q.266 Unattempt
If 13.6 eV energy is required to ionize the hydrogen atom, then the energy required to remove an electron from n = 2 is
[2002]
If 13.6 eV energy is required to ionize the hydrogen atom, then the energy required to remove an electron from n = 2 is
[2002]
Q.267 Correct
Q.267 In-correct
Q.267 Unattempt
At a specific instant emission of radioactive compound is deflected in a magnetic field. The compound can emit
(i) electrons
(ii) protons
(iii) He‌2+
(iv) neutrons
The emission at instant can be
[2002]
At a specific instant emission of radioactive compound is deflected in a magnetic field. The compound can emit
(i) electrons
(ii) protons
(iii) He‌2+
(iv) neutrons
The emission at instant can be
[2002]
Q.268 Correct
Q.268 In-correct
Q.268 Unattempt
If N0 is the original mass of the substance of half-life period t1∕2=5 years, then the amount of substance left after 15 years is
[2002]
If N0 is the original mass of the substance of half-life period t1∕2=5 years, then the amount of substance left after 15 years is
[2002]
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