Atoms

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. In the light of the above statements, choose the correct answer from the options given below

1. A is true but R is false
2. Both A and R are true and R is the correct explanation of A
3. A is false but R is true
4. Both A and R are true but R is NOT the correct explanation of A

An electron in the hydrogen atom initially in the fourth excited state makes a transition to nth energy state by emitting a photon of energy 2.86 eV. The integer value of n will be .

Considering Bohr's atomic model for hydrogen atom : Choose the correct answer from the options given below :

1. (A), (B) only
2. (A), (D) only
3. (A), (C) only
4. (B), (D) only

Assuming the validity of Bohr's atomic model for hydrogen-like ions the radius of Li++ ion in its ground state is given by 1Xa0, where X = (Where a0 is the first Bohr's radius.)

1. 2
2. 9
3. 1
4. 3

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

1. 3
2. 6
3. 1
4. 0

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

1. 1n4
2. 1n2
3. 1n3
4. 1n

During the transition of electron from state A to state C of a Bohr atom, the wavelength of emitted radiation is 2000 and it becomes 6000 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

1. 4000
2. 6000
3. 2000
4. 3000

An electron in the ground state of the hydrogen atom has the orbital radius of 5.3 10-11 m while that for the electron in third excited state is 8.48 10-10 m. The ratio of the de Broglie wavelengths of electron in the ground state to that in the excited state is

1. 4
2. 3
3. 9
4. 16

A hydrogen atom in ground state is given an energy of 10.2 eV. How many spectral lines will be emitted due to transition of electrons?

1. 3
2. 6
3. 10
4. 1

In an alpha particle scattering experiment distance of closest approach for the particle is 4.5 10-14 m. If target nucleus has atomic number 80 , then maximum velocity of -particle is 105 m/s approximately. ( 14 0 = 9 109 SI unit, mass of particle = 6.72 10-27 kg)