Chemistry Test 4

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Chemistry Test 4

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Question 1/6
4 / -1

Which of the following is the wavelength of the electron in the nth Bohr orbit?

Correct

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A
N x 0.529 angstrom

Correct

Wrong

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B
N x 2 x 3.146 x 0.529 angstrom

Correct

Wrong

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C
(N x 2 x 3.146 x 0.529)² angstrom

Correct

Wrong

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D
(N x 2 x 3.146 x 0.529)³ angstrom

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Solutions

Wavelength = h/mv

mvr_n = nh/2pi

2pi (r_n) = nh/mv = n x wavelength

r_n = n²r

n 2 pi (r) = wavelength
Question 2/6
4 / -1

Which of the following statement is incorrect about the Arrhenius equation?

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A
The pre-exponential factor and the activation energy are independent of temperature.

Correct

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B
With the increase in the temperature, there is an increase in the number of molecules having high energies.

Correct

Wrong

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C
The effective collisions and the molecules with a threshold energy are proportional to each other.

Correct

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D
The rate constant is dependent on temperature.

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Solutions

The pre-exponential factor and the activation energy are dependent on temperature as they both are related to the molecular collision which in turn is dependent on temperature.
Question 3/6
4 / -1

What will be the time taken to complete 75% of the reaction when the half-life of that first order reaction is 5 minutes?

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A
7 minutes

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B
7.5 minutes

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C
10 minutes

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D
15 minutes

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Solutions

100% to 50% = 5 minutes (Half life)

50% to 25% i.e. another half life will also be equal to 5 minutes.

Therefore, the time taken to complete 75% of the reaction = 5 + 5 = 10 minutes
Question 4/6
4 / -1

In which of the following cases, maximum amount of work is done?

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A
Isothermal expansion of an ideal gas

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B
Adiabatic expansion of an ideal gas

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Wrong

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C
Isothermal expansion of a real gas

Correct

Wrong

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D
Adiabatic expansion of a real gas

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Solutions

This is because in the adiabatic expansion, the temperature decreases whereas in the isothermal expansion, the temperature remains the same.
Question 5/6
4 / -1

Which of the following conditions is incorrect in the case of the entropy to be zero for a pure solid?

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A
The pure solid must be crystalline and not amorphous.

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B
The solid must be an element.

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C
A consistent ordering must be present.

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D
The temperature must be 0 K

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Solutions

The only conditions required for entropy to be zero are:

a) T must be 0K

b) The solid must be crystalline.

c) The solid must be ordered within its lattice.
Question 6/6
4 / -1

Which of the following is incorrect about chemical equilibrium?

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A
The rate of forward reaction is equal to the rate of the backward reaction.

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B
The equilibrium is possible from both the sides.

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C
The process is not dynamic in nature.

Correct

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D
Under similar condition of temperature, concentration and pressure, the same state of equilibrium is reached.

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Solutions

The chemical equilibrium is dynamic in nature as the reaction is never ceased because reaction occurs in both directions with equal rates.

Question 1/6

N x 0.529 angstrom

N x 2 x 3.146 x 0.529 angstrom

(N x 2 x 3.146 x 0.529)² angstrom

(N x 2 x 3.146 x 0.529)³ angstrom

Question 2/6

The pre-exponential factor and the activation energy are independent of temperature.

With the increase in the temperature, there is an increase in the number of molecules having high energies.

The effective collisions and the molecules with a threshold energy are proportional to each other.

The rate constant is dependent on temperature.

Question 3/6

7 minutes

7.5 minutes

10 minutes

15 minutes

Question 4/6

Isothermal expansion of an ideal gas

Adiabatic expansion of an ideal gas

Isothermal expansion of a real gas

Adiabatic expansion of a real gas

Question 5/6

The pure solid must be crystalline and not amorphous.

The solid must be an element.

A consistent ordering must be present.

The temperature must be 0 K

Question 6/6

The rate of forward reaction is equal to the rate of the backward reaction.

The equilibrium is possible from both the sides.

The process is not dynamic in nature.

Under similar condition of temperature, concentration and pressure, the same state of equilibrium is reached.

Question 1/6

N x 0.529 angstrom

N x 2 x 3.146 x 0.529 angstrom

(N x 2 x 3.146 x 0.529)2 angstrom

(N x 2 x 3.146 x 0.529)3 angstrom

Question 2/6

The pre-exponential factor and the activation energy are independent of temperature.

With the increase in the temperature, there is an increase in the number of molecules having high energies.

The effective collisions and the molecules with a threshold energy are proportional to each other.

The rate constant is dependent on temperature.

Question 3/6

7 minutes

7.5 minutes

10 minutes

15 minutes

Question 4/6

Isothermal expansion of an ideal gas

Adiabatic expansion of an ideal gas

Isothermal expansion of a real gas

Adiabatic expansion of a real gas

Question 5/6

The pure solid must be crystalline and not amorphous.

The solid must be an element.

A consistent ordering must be present.

The temperature must be 0 K

Question 6/6

The rate of forward reaction is equal to the rate of the backward reaction.

The equilibrium is possible from both the sides.

The process is not dynamic in nature.

Under similar condition of temperature, concentration and pressure, the same state of equilibrium is reached.

(N x 2 x 3.146 x 0.529)² angstrom

(N x 2 x 3.146 x 0.529)³ angstrom