NEET(UG) - 2021 SIR
CHEMISTRY Selective Interactive Revision
Worksheet - 22 (Lecture-1) Topic : Atomic Structure
1. The ratio of specific charge of a proton and an –particle is :–
(1) 2 : 1 (2) 1 : 2 (3) 1 : 4 (4) 1 : 1
2. Atomic weight of Ne is 20.2. Ne is mixture of 20 Ne and 22 Ne, relative abundance of heavier isotope is :-
(1) 90 (2) 20 (3) 40 (4) 10
231
3. Number of protons, neutrons & electrons in the element 89 is :-
(1) 89, 231, 89 (2) 89, 89, 242 (3) 89, 142, 89 (4) 89, 71, 89
4. The energy of one mole photons of radiation having frequency 5.01 × 1014 Hz is :
(1) 160 KJ mol–1 (2) 180 KJ mol–1 (3) 200 KJ mol–1 (4) 220 KJ mol–1
5. Angular momentum in second Bohr orbit of H-atom is x. Then find out angular momentum in
Ist excited state of Li+2 ion :
x
(1) 3x (2) 9x (3) (4) x
2
6. The ratio of the radii of two Bohr orbits of H-atom is 4 : 1, what would be their nomenclature :-
(1) K & L (2) L & K (3) N & L (4) 2 & 3 both
7. Maximum frequency of emission is obtained for the transition :–
(1) n = 2 to n = 1 (2) n = 6 to n = 2 (3) n = 1 to n = 2 (4) n = 2 to n = 6
8. The ionisation potential of the hydrogen atom is 13.6 eV. The energy needed to ionise a hydrogen
atom which is in its second excited state is about:-
(1) 13.6 eV (2) 10.2 eV (3) 3.4 eV (4) 1.51 eV
9. Third line of Balmer series is produced by which transition in spectrum of H–atom
(1) n = 5 to n = 2 (2) n = 5 to n = 1 (3) n = 4 to n = 2 (4) n = 4 to n = 1
10. Which series have highest energy in hydrogen spectrum :-
(1) Balmer (2) Brackett (3) Pfund (4) Lyman
11. The limiting line in Balmer series will have a frequency of :-
(1) 3.65 × 1014 sec–1 (2) 3.29 × 1015 sec–1 (3) 8.22 × 1014 sec –1 (4) –8.22×10 14 sec –1
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NEET(UG) - 2021 SIR
CHEMISTRY Selective Interactive Revision
Worksheet - 22 (Lecture-1) Topic : Atomic Structure
12. In H–atom, electron transits from 6 th orbit to 2 nd orbit in multi step. Then total spectral lines
(without Balmer series) will be :–
(1) 6 (2) 10 (3) 4 (4) 0
13. An electron has a kinetic energy of 2.8×10–23 J. de-Broglie wavelength will be nearly :-
(me = 9.1 × 10 –31 kg)
(1) 9.28 × 10–24 m (2) 9.28 × 10–7 m (3) 9.28 × 10–8 m (4) 9.28 × 10–10 m
14. What is the ratio of the de-Broglie wavelengths for electrons accelerated through 200 volts and
50 volts :-
(1) 1 : 2 (2) 2 : 1 (3) 3 : 10 (4) 10 : 3
15. A 0.66 kg ball is moving with a speed of 100 m/s. The associated wavelength will be
(h = 6.6 × 10–34 Js) :-
(1) 6.6 × 10 –34 m (2) 1.0 × 10 –35 m (3) 1.0 × 10 –32 m (4) 6.6 × 10 –32 m
Z2
16. Based on equation E = –2.178 × 10–18 J certain conclusions are written. Which of them is not
n2
correct ?
(1) For n = 1, the electron has a more negative energy than it does for n = 6 which means that the
electron is more loosely bound in the smallest allowed orbit.
(2) The negative sign in equation simply means that the energy of electron bound to the nucleus is
lower than it would be if the electrons were at the infinite distance from the nucleus
(3) Larger the value of n, the larger is the orbit radius
(4) Equation can be used to calculate the change in energy when the electron change orbit
17. 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 × 10–18 J atom–1) :-
(1) 1·03 × 1015 s–1 (2) 3·08 × 1015 s–1 (3) 2·00 × 1015 s–1 (4) 1·54 × 1015 s–1
18. Uncertainty in position of a 0.25 g particle is 10–5 m. Then uncertainty in its velocity will be:-
(h = 6.6 × 10–34 Js) :-
(1) 1.2 × 1034 m/s (2) 2.1 × 10–26 m/s (3) 1.6 × 10–20 m/s (4) 1.7 × 10–9 m/s
19. The frequency of light emitted for the transition n = 4 to n = 2 of He+ is equal to the transition in
H atom corresponding to which of the following :-
(1) n = 3 to n = 1 (2) n = 2 to n = 1 (3) n = 3 to n = 2 (4) n = 4 to n = 3
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CHEMISTRY Selective Interactive Revision
Worksheet - 22 (Lecture-1) Topic : Atomic Structure
20. A single electron orbits a stationary nucleus of charge +Ze, where Z is a constant. It requires
47.2 eV to excite electron from second Bohr orbit to third Bohr orbit, find the value of Z :-
(1) 1 (2) 3 (3) 5 (4) 4
21. If uncertainty in position and momentum are equal, then uncertainty in velocity is ?
h 1 h h 1 h
(1) (2) (3) (4)
2m 2 m
22. Be+3 and a proton are accelerated by the same potential, their de-Broglie wavelengths have the ratio:
(Assume mass of proton = mass of neutron)
(1) 1 : 2 (2) 1 : 4 (3) 1 : 1 (4) 1 : 3 3
23. A single electron in an ion has ionisation energy equal to 217.6 eV. What is the total number of neutrons
present in that ion is :-
(1) 2 (2) 4 (3) 5 (4) 9
24. The circumference of the 4th Bohr orbit in hydrogen atom is 5.32 nm. The de Broglie wavelength
of the electron revolving in this orbit is :-
(1) 0.133 nm (2) 13.3 nm (3) 1.33 nm (4) 133 nm
25. The uncertainties in the velocities of two particles, A and B are 0.05 and 0.02 ms–1 , respectively.
xA
The mass of B is five times to that of the mass of A. What is the ratio of uncertainties in their
xB
positions?
(1) 2 (2) 0.25 (3) 4 (4) 1
26. A gas absorb a photon of 355 nm and emits at two wavelengths. If one of the emission is at 680 nm,
the other is at :-
(1) 518 nm (2) 1035 nm (3) 325 nm (4) 743 nm
27. Ratio of time period of e– in 2nd orbit of H atom and 3rd orbit of He+ is :
(1) 4/27 (2) 8/9 (3) 27/5 (4) 32/27
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