CSIR-JRF/NET-Physical Science

Atomic and Molecular Physics test-7

Answer all questions Time 30 min
Max 20 marks

1 Energy levels A , B, C of a certain atom correspond to increasing values of energy, that is, EA a) λ3 =λ1 + λ2 b) λ3 =λ1. λ2/( λ1 + λ2 )
c) λ1 +λ2 + λ3 =0 d) λ3 =(λ1 + λ2)/2
2 For H-atom, in the lowest energy level, the angular momentum of the electron is
a) h/2π b) h/π c)2 h/π d) 2π/h

3 The angular momentum of the electron in the nth orbit is given by
a) nh b) h/2π n c) nh/2π d) 2π/nh
4 The energy required to remove an electron in a H-atom from n=10 state is
a) 13.6eV b) 1.36eV c) 0.136eV d) 0.0136eV

5 If EN and JN denote the total energy magnitude and angular momentum of an electron in the nth orbit of a Bohr atom, then
a) EN α JN b) EN α 1/JN c) EN α JN2 d) EN α JN2

6 Ionisation potential of hydrogen is 13.6eV. H-atom in the ground state are excited by monochromatic radiation of energy 12.1eV. The spectral lines emitted by hydrogen atom according to Bohr’s theory will be
a) one b) two c) three d) four

7 The ground state energy of H-atom is 13.6eV. The energy needed to ionise H-atom in its second excited state is
a) 1.51eV b) 0 c) -13.6eV d) 6.8eV

8 The total energy of the electron in the H-atom in the ground state is -13.6eV. The KE of this electron is
a) 13.6 b) 0 c) -13.6eV d) 3.4eV

9 The energy levels of a certain atom for first, second and third levels are E, 4E/3 and 2E respectively. A photon of wavelength λ is emitted for a transition 3 to 1. What will be the wavelength of emission for transition 2 to 1
a) λ/ 3 b) 4λ/ 3 c) 3λ/ 4 d) 3λ
10 The series limit of Balmer series is 640nm. The series limit of Paschen series will be
a) 1868nm b) 6400nm c) 240nm d) 1440nm