STRUCTURE OF ATOM
Single Answer Type :
1. As the number of orbit increases from the nucleus, the difference between the adjacent
energy levels
(A) increases (B) remains constant
(C) decreases (D) disintegration
2. If the speed of electron in the Bohr’s first orbit of hydrogen atom is x, the speed for the
electron in the third Bohr’s orbit is
(A) x/9 (B) x/3 (C) 3x (D) 9x
3. The ratio of the radius of the first Bohr orbit for the electron orbiting around the hydrogen
nucleus that of the electron orbiting around the deuterium nucleus is approximately
(A) 1 : 1 (B) 1 : 2 (C) 2 : 1 (D) 1 : 4
4. The ratio of the radii of the first three Bohr orbit is
(A)1 : 0.5 : 0.33 (B) 1 : 2 : 3 (C) 1 : 4 : 9 (D) 1 : 8 : 27
5. The radius of the first orbit in hydrogen is 0.53A0 So the radius of the second orbit in He
is
(A) 1.06A0 (B) 2.12 A 0 (C) 0.53 A0 (D) 2.38 A 0
6. In the ground state of hydrogen atom the potential energy is
(A) -3.4 eV (B) -10.2 eV (C) -13.6 eV (D) -27.2 eV
7. The velocity of the electron with second Bohr orbit of the hydrogen atom is
(A) 2.19 108 cm sec 1 (B) 1.095 108 cm sec 1
(C) 0.73 108 cm sec 1 (D) 1.095 108 cm sec 1
8. The electron level which allows the hydrogen to absorb photons but not to emit is
A) 1s B) 2s C) 2p D) 3d
9. Change in angular momentum when an electron makes a transition corresponding to the
3rd line of the Balmer series in Li2+ ion is
h 2h 3h 4h
A) B) C) D)
2 2 2 2
10. Which of the following statements does not form a part of Bohr’s model of hydrogen atom?
A) Energy of the electrons in the orbits is quantized
B) The electron in the orbit nearest the nucleus has the lowest energy
C) Electrons revolve in different orbits around the nucleus
D) The position and velocity of the electrons in the orbit cannot be determined
simultaneously
11. Correct order of radius of the Ist orbit of H, He , Li2 , Be3 is
A) H He Li2 Be3 B) Be3 Li2 He H
C) He Be3 Li2 H D) He H Li 2 Be3
12. What is likely to be orbit number for a circular orbit of diameter 20.74 nm of the hydrogen
atom :
A) 10 B) 14 C) 12 D) 16
13. The energy of an electron in the first Bohr orbit of H atom is – 13.6 eV. The possible energy
value of the excited state for electrons in Bohr orbits of hydrogen is
A) -3.4 eV B) -4.2 eV C) -6.8 eV D) + 6.8 eV
1
14. What is the potential energy of the electron in the L-shell of the hydrogen atom?
A) -13.6eV B) -6.8eV C) -10.2eV D) -3.4eV
15. The energy of the electron at infinite distance from the nucleus in Bohr’s model is taken as
A) Zero B) Positive C) Negative D) Any value
16. The ratio of the energy of the electrons in ground state of hydrogen to the electrons in first
excited state of Be3 is :
A) 1:4 B) 1:8 C) 1:16 D) 16:1.
17. Energy of the electron in hydrogen atom in some excited state is -3.4 eV. What will be its
angular momentum?
A) 1.8 10 30 kgm 2s 1 B) 2.1 10 34 kgm 2s 1
C) 9.2 10 37 kgm 2s 1 D) 1.2 10 32 kgm 2s 1
18. If the value of En in hydrogen atom is – 78.4 kcal/mole, the orbit number is
A) 4 B) 3 C) 2 D) 1
19. For ionizing an excited hydrogen atom, the minimum energy required in eV will be
A) 3.4 or less B) More than 13.6
C) between 3.4 to 10.2 D) between 10.2 to 13.6
20. In an atom, two electrons move round the nucleus in circular orbits of radii R and 4R. The
ratio of the times taken by them to complete one revolution is (Consider Bohr model to be
valid)
A) 1 : 4 B) 4 : 1 C) 1 : 8 D) 8 : 1
21. The separation energy of the electron present in the shell n = 3 is 1.51 eV. What is the
energy in the first excited state?
A) -1.51eV B) -3.4eV C) +1.51 D) +3.eV
22. Energy levels A, B, C of a certain atom correspond to increasing values of energy,
i.e., E A E B E C . If 1 , 2 and 3 are the wavelengths of radiations corresponding to the
transitions C to B, B to A and C to A respectively, which of the following statement is
correct:
1 2
D) 3 1 2
2 2 2
A) 3 = 1 + 2 B) 3 = C) 1 + 2 + 3 = 0
1 + 2
MULTIPLE CORRECT OPTION TYPE :
23. Choose the correct relations on the basis of Bohr’s theory
1 1
A) Velocity of electron B) Frequency of revolution 3
n n
1
C) Radius of orbit n Z
2
D) Electrostatic force on electron
n4
24. A hydrogen - like atom has ground state binding energy 122.4eV. Then
A) its atomic number is 3
B) a photon of 90eV can excite it to a higher state
C) an 80eV photon cannot excite it to a higher state
D) its atomic number is 5
2
25. The change in angular momentum corresponding to an electron in Balmer transition
inside a hydrogen atom can be
h h h 3h
A) B) C) D)
4 2
26. Identify the correct statement(s) among the following
A) Potential energy of a system of two opposite charges increases with the decrease in
distance.
B) When an electron makes a transition from higher orbit to lower orbit, it's kinetic energy
increases.
C) When an electron makes a transition from lower energy to higher energy state, its
potential energy increases.
D) 11eV photon can free an electron from the 1 st excited state of He+ ion.
INTEGER TYPE
27. The energy of an electron in the first Bohr orbit of H-atom is -13.6eV. What is the possible
value of principal quantum number for the excited state of have energy -3.4eV?
28. When an electron transits from 2E to ‘E’ energy level the wavelength of photon produced is
4E
1 . If electronic transition involves to E level, the wavelength of resultant photon ‘ 2 ’.
3
2 is how many times greater than ‘ 1 ’.
Comprehension
When an electric discharge is passed through hydrogen, the molecule is dissociated into
atoms, in many of which electrons are raised to high energy levels, which such electrons
falls back to lower energy levels, a series of spectral lines are emitted. These different
spectral lines of different wavelengths are observed in different regions e.g. U.V. visible,
I.R. the wavelengths of different lines of different series can be determined by.
1 1 1
RZ 2 2 2 where R = 1.097 107 m-1
n1 n2
29. If a photon of wavelength 200 pm strikes an atom and one of the inner bound electrons is
ejected out with a velocity of 2 107 ms-1, calculate the energy with which it is bound to
nucleus?
A) 5057 eV B) 50.75 eV C) 5.075 eV D) 507.5 eV
30. A hydrogen like species with atomic number Z is in higher excited state “n” and emits
photons of energy 25.7 eV and 8.7 eV when makes a transitions to 1 st and 2nd excited state
respectively. Determine “n”?
A) 4 B) 5 C) 3 D) 2
Key
1. C 2. B 3. A 4. C 5. A 6. D 7. B
8. A 9. C 10. D 11. A 12. B 13. A 14. B
15. A 16. A 17. B 18. C 19. A 20. C 21. B
22. B 23. ABD 24. AC 25. BCD 26. BC 27. 2 28. 3
29. A 30. B
