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The frequency of radiation emitted when the electron falls from n = 4 to n = 1 in a hydrogen atom will be (Given ionization energy of H=2.18 ×10–18J atom–1and h = 6.625 × 10–34 J s ) [2004]
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What is the mass of carbon dioxide which contains the same number of molecules as are contained in 40 g of oxygen?
The density of a gas is 1.78 g L-1 at STP. The weight of one mole of gas is
1 mole occupies a volume of 22.4 L at STP
Mass of 1 mole of a gas = Density x Volume
= 1.78 x 22.4 = 39.9 g
The following quantum numbers are possible for how many orbital (s) n = 3, l = 2, m = +2 ? [2001]
The value of Planck's constant is 6.63 × 10–34 Js.The velocity of light is 3.0 × 108 m s–1. Which value is closest to the wavelength in nanometers of a quantum of light with frequency of 8 × 1015 s–1 ? [2003]
The Mass of Atom is entirely due to ________.
The mass of an atom is entirely due to its Nucleus.
Nucleus consists of protons and neutrons together known as nucleons.
An atom consists of a proton, neutron, and electron.
While calculating the mass of an atom, the mass of electron is neglected due to its relatively insignificant mass.
Mass of proton : 1.6727 X 10-27 kg.
Mass of electron : 9.1093 X 10-31 kg.
Mass of neutron : 1.6727 X 10-27 kg.
Protons and neutrons have approximately same mass.
The element having tetra-atomic atomicity is ______ .
Key Points
The present number of atoms in any molecule of an element is called its atomicity.
Tetra atomic elements are those which are made up of four atoms.
Phosphorous exists as molecules made up of four atoms in a tetrahedral structure.
Each phosphorus molecule consists of four atoms of phosphorus.
Alkali metals are assigned which group in the Modern Periodic Table?
Group 1 elements in the Periodic table are known as Alkali metals
They have ns1 outermost configuration and belong to the S-block Elements.
They also have a strong tendency to donate their valence electrons in the outermost shell to form strong ionic bonds.
It contains elements from Lithium (Li) to Francium (Fr).
Who was the first to propose Atomic Theory?
What is common among Lithium, Sodium and Potassium?
Lithium (Li), Sodium (Na), and Potassium (K) has one electron in their outermost orbits.
They belong to group 1 and hence they are Alkali Metals and not alkali earth metal.
Lithium can form lithium oxide, Sodium forms Sodium oxide and Potassium can form Potassium peroxide in the presence of oxygen.
They are not Inert elements as they react with other compounds.
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