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Test No. 18 ATOMIC SPECTRA /LINE SPECTRA
1. The electron of hydrogen atoms is in 3rd orbit, then how many different series it can
emit
(a) 4 (b) 3 (c) 2 (d)1
2. The electron of hydrogen atoms is in 4th excitation state then how many lines it may
emit
(a) 10 (b) 6 (c) 8 (d) 4
th
3. The electron of hydrogen atoms is in 4 energy level then how many lines it may
emit
(a) 10 (c) 6 (c) 8 (d) 4
rd
4. The energy of electron in 3 excitation state is _________
(a) -13.6 eV (b) -3.4 eV (c) -1.85 eV (d) -0.85 eV
5. The energy of an electron of hydrogen atom is -0.85 eV, find the quantum of energy
state
(a) 3 (b) 4 (c) 2 (d) 5
6. In lowest energy level of hydrogen atom, the angular momentum of hydrogen
electron is
(a) h/2𝜋 (b) h/3𝜋 (c) 3h/2𝜋 (d) h/𝜋
nd
7. The energy required by electron to excite from ground state to 2 excitation state is
(a) 10.2 eV (b) 12.1eV (c) 12.75eV (d) 13.6 eV
8. The ionization potential of hydrogen atom is __________
(a) 13.6 J (b) 13.6 eV (c) 13.6 V (d) A.O.T
9. For the hydrogen atom, the energy of radiation emitted in the transition from fourth
excited state to second excited state is
(a) 0.57 eV (b) 0.67 eV (c) 0.97 eV (d) 1.27 eV
10. The radius of second orbit of hydrogen atom is R, the radius of the third orbit will
be
(a) 3R (b) 2.25R (c) 9R (d) R/3
11. Ionization potential of hydrogen is 13.6eV. If is excited by a photon of energy 12.1eV
, then number of lines in the emission spectrum is
(a) 2 (b) 4 (c) 3 (d) 5
12. The Balmer series is obtained when all the transition of electron terminate on
(a) 1st orbit (b) 2nd orbit (c) 3rd orbit (d) 4th orbit
th
13. When all transition of electron of hydrogen atom terminate at 4 orbit, then
correspondence series is _____
(a) lyman (b) Balmer (c) Paschen
(d) Pfund (e) Bracket
14. When an electron makes transition from ground state to an excitation state then
(A) its K.E decrease and P.E increases (b) its K.E increase and P.E decrease
(C) its K.E and P.E both increases (d) its K.E and P.E both decreases
15. The measurement of wave length and intensity of the electromagnetic radiation
emitted or absorbed by atom is known as
(a) Atomic spectra (b) atomic nucleus

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Test No. 18 ATOMIC SPECTRA /LINE SPECTRA
(c) radioactivity (d) nuclear reaction
16. Electrons in the atom are held to the nucleus by
(a) coulomb’s force (b) nuclear force
(c) vander waal’s force (d) gravitational force
17. The angular momentum of electron in any orbit is always equal to :
(a) h/2𝜋 (b) nh/2𝜋 (c) 2𝜋/ℎ (d) h/𝜋
18. When hydrogen atom is in its first excited level, it’s radius is
(a) four times, it ground state radius (b) twice times, it ground state radius
(c) same times, it ground state radius (d) half times, it ground state radius.
19. As an electron makes a transition from an excited state to the ground state of a
hydrogen
(a) kinetic energy decreases, potential energy increases but total energy remains
same
(b) kinetic energy and total energy decrease but potential energy remains same
(c) its kinetic energy increases but potential energy and total energy decreases
(d) kinetic energy, potential energy and total energy decrease
20. According to Neil Bohr’s atomic model :
(a) Electron never losses energy
(b) Electron losses energy when jumps from higher energy level to lower energy level
(c) Electron losses energy as long as it is revolving around nucleus
(d) Electron gains energy when jumps from higher energy level to lower energy level
21. In Hydrogen atom, which of the following electronic transitions would involve the
maximum energy change
(a) n = 2 to n = 1 (b) n = 3 to n = 1
(c) n = 4 to n = 2 (d) n = 3 to n = 2
22. Hydrogen atom excites energy level from fundamental state to n = 3, number of
spectral lines according to Bohr, is
(a) 4 (b) 3 (c) 1 (d) 2
23. The ratio of radii of the first three Bohr orbits is
(a) 1 : ½ : ¼ (b) 1 : 2 : 3 (c) 1 : 4 : 9 (d) 1: 4 : 25

24. The amount of energy needed to transfer electron from first orbit to third orbit is:
(a) 13.6 eV (b) 3.4 eV (c) 12.09 eV (d) 1.51 eV
25. The energy of a photon ejected when the electron jumps n = 3 state to n = 2 state of
hydrogen is approximately:
(a) 1.9 eV (b) 1.5 eV (c) 0.85 eV (d) 3.4 eV
26. A photon of energy 12.4 eV is completely absorbed by a hydrogen atom initially in
the ground state so that it is excited. The quantum number of the excited state is…
(a) n =1 (b) n= 3 (c) n = 4 (d) n = 
27. when an electron jumps from 3rd orbit to 1st orbit in the hydrogen atom, the lines
spectrum obtained belongs to :
(a) Bracket series (b) lyman series (c) Balmer series (d) Paschen series
28. Brackett series of hydrogen spectrum lies in
(a) Ultraviolet region (b)Visible region (c) Infrared region (d) x- rays
29. Hydrogen atom spectrum consists of lines in

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Test No. 18 ATOMIC SPECTRA /LINE SPECTRA
(a) Ultraviolet region (b)Visible region (c) Infrared region (d) A.O.T
30. In hydrogen atom Ballmer’s series is obtained when electron falls into :
(a) n=1 (b) n=2 (c) n=3 (d) n=4
31. According to Bohr’s theory, an electron revolving around the nucleus in a fixed orbit
(a) radiate Energy (b) remains stationary (c) Absorb energy (d) emit no energy
32. spectral lines in the Balmer series of hydrogen atom lies in the region of :
(a) Ultraviolet (b) visible (c) Infrared (d) x-rays
33. according to the Bohr’s theory, angular momentum of electron is integral multiple of
(a) h (b) h (c) 1/h (d) 1/ h
34. Radius of 1st orbit of hydrogen atom is 0.53 0A, then the radius of fifth state of
hydrogen atom is …
(a)2.650A (b)13.250A (c)200A (d)9650A
35. wave length of maximum radiant energy in hydrogen atom spectrum belongs to :
a) Balmer (b) laymen (c) Pashen (d) Pfund
36. which of the following transition in hydrogen atoms emits Photon of highest
frequency?
(a) n=2 to n=6 (b) n=1 to n=2 (c) n=2 to n=1 (d) n=6 to n=2
37. Which one is the postulate of Bohr Theory?
I. .Electron does not emit light when it jumps
from higher energy level to lower energy level
II. .Electron emits energy while moving in orbit
III. .Electron does not emit energy while
moving in orbit
IV. Electron never loss it energy in an atom
(a) only I (b) only II (c)only III & IV (d) only III
38. Excited atoms return to their ground state in……
a) 10-10s (b) 10-8s (c) 10-6s (d) 10-9s
39. Total number of series in hydrogen spectrum is……
a) three (b) four (c) five (d) six
40. The radiations emitted from hydrogen filled discharge tube shows….
a) band spectrum (b) line spectrum
(c) continuous spectrum d) absorption spectrum
41. The electric P.E of an electron in an orbit at a distance r from the positive charge
a) -Ke/r (b) -Ke2/r2 (c)-Ke2/r (d) -Ke2/r2
42. Radiation with wavelength longer than red lights
a) ultraviolet rays (b) X-rays (c) infrared radiation (d)visible radiation
43. Electron in the atom are held in the atom due to
(a) Coulombs force (b) nuclear force
(c) atomic force (d) both a and b
44. Which color has the shortest wavelength of light?
(a) Red (b) Yellow (c) Blue (d) Green
45. Listed below are five phenomena connected with photons and/or charged particles;
1. Alpha – particle emission 2. Beta – particle emission
3. Line emission spectra 4. Line absorption spectra
5. Electron diffraction

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Test No. 18 ATOMIC SPECTRA /LINE SPECTRA
Which of these phenomena give direct evidence for the existence of discrete electronic
energy levels in atoms?
(a) 1 & 5 (b)2 & 3 (c) 3 and 4 only (d) 2,3,4 and 5 only

46. Hydrogen atoms are excited from ground state of the principal quantum number 4.
Then the number of spectral lines observed will be
(a) 3 (b) 6 (c) 5 (d) 2
47. Which of the following phenomena suggests the presence of electron energy levels in
atoms
(a) Radio active decay (b) Isotopes
(c) Spectral lines (d) alpha -particles scattering
48. Which of the following spectral series in hydrogen atom give spectral line of 4860 Å
(a) Lyman (b) Balmer (c) Paschen (d) Brackett
49. Energy of electron in a orbit of H-atom is
(a) Positive (b) Negative (c) Zero (d) Nothing can be said.
50. The concept of stationary orbits was proposed by
(a) Neil Bohr (b) J.J. Thomson (c) Ruther ford (d) I. Newton
51. According to classical theory, the circular path of an electron in Rutherford atom is
(a) Spiral (b) Circular (c) Parabolic (d) Straight line
52. Energy of the electron in nth orbit of hydrogen atom is given by -13.6/n2 eV. The
amount of energy needed to transfer electron from first orbit to third orbit is
(a) 13.6 eV (b) 3.4 eV (c) 12.09 eV (d) 1.51 eV
53. Whenever a hydrogen atom emits a photon in the Balmer series
(a) It need not emit any more photon
(b) It may emit another photon in the Paschen series
(C)It must emit another photon in the Lyman series
(d) It may emit another photon in the Balmer series
54. Which of the following is NOT one of the conclusions drawn by Rutherford after his
alpha scattering experiment?
(A) There is a large space between the nucleus of the atom and the electrons.
(B) The electrons orbit the nucleus of the atom.
(C) The nucleus is positively charged.
(D) The atom is neutral.
(E) Electrons can change orbits when they absorb or emit energy.
55. An emission spectrum is produced when
(A) electrons in an excited gas jump up to a higher energy level and release photons.
(B) electrons in an excited gas jump down to a lower energy level and release photons.
(C) electrons are released from the outer orbitals of an excited gas.
(D) an unstable nucleus releases energy.
(E) light is shined on a metal surface and electrons are released.
56. The single electron in an atom has an energy of −40 eV when it’s in the ground state,
and the first excited state for the electron is at −10 eV. What will happen to this
electron if the atom is struck by a stream of photons, each of energy 15 eV?

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Test No. 18 ATOMIC SPECTRA /LINE SPECTRA
(A) The electron will absorb the energy of one photon and become excited halfway to the
first excited state, then quickly return to the ground state, without emitting a photon.
(B) The electron will absorb the energy of one photon and become excited halfway to the
first excited state, then quickly return to the ground state, emitting a 15 eV photon in
the process.
(C) The electron will absorb the energy of one photon and become excited halfway to the
first excited state, then quickly absorb the energy of another photon to reach the first
excited state.
(D) The electron will absorb two photons and be excited to the first excited state.
(E) Nothing will happen.
1  1 1 
57. the formula =R  − , “R” is knownas _______ constant
n 2 2
n2 
a) Bohr’s b) Rydberg’s c) John’s d) None of these
58. The formula for “Paschen” series for hydrogen spectrum is _______ when, n = 4,5,6,
_______
= R  2 − 2  b) = R  2 − 2  = R  2 − 2  d) N.O.T
1 1 1 1 1 1 1 1 1
a) c)
 3 n   2 n   4 n 
59. When an electron in hydrogen atom jumps from higher orbit into second orbit. The
set of lines emitted is called _______
a) Balmer series b) Lyman series c) Joule series d) None of these
60. Lyman series lies in _______
a) Visible region b) infrared c) Ultraviolet region d) x-rays
61. The formula for nth number of orbit for hydrogen atom is _______ when n = 1,2,3,
1 n 2h 2 n2 h2
a) rn = .e2K b) rn = c) rn = d) rn =
4  0 4 Ke m
2 2
4 Ke m
2 2
 Ke 2 m
2

62. The first ground state energy “E1” is given as ______

a) 1.43 ev b) -13.6 ev c) 4.13 ev d) 3.136 ev
63. The value of third ground state energy “E3” is given as _______:
a) -1.51 ev b) 1.51 ev c) 5.15 ev d) 1.63 ev
64. The radiation emitted from hydrogen filled discharge tube, when viewed by
dispersing devices such as prism, gratings etc. shows ______:
a) a line spectrum b) continuous spectrum c) band spectrum d) A.O.T
65. According to Bohr’s theory of hydrogen atom the speed vn of an electron is given by
the equation:
h ke 2 h2 he 2
a) vn = n b) vn = n c) vn = n d) vn = n
2 m rn 2 m rn 2 2 m rn 2 m rn
66. Balmer series lies in:
a) Visible region b) Ultraviolet region c) Infrared region d) N.O.T
67. Mathematically Balmer series is represented as, where R is called Rydberg’s
constant:
 1 1 
= R  2 − 2  , n = 3,4
1 1 1 1
a) =R  − , n = 2,3,4 b)
n 1 2
n2  n 2 n 

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Test No. 18 ATOMIC SPECTRA /LINE SPECTRA

= R  2 − 2  , n = 4,3,4 = R  2 − 2  , n = 5,3,4
1 1 1 1 1 1
c) d)
n 3 n  n 4 n 
68. Mathematically Lyman series is represented as, where R is called Rydberg’s constant:
 1 1 
= R  2 − 2  , n = 3,3,4
1 1 1 1
a) =R  − , n = 2,3,4 b)
n 1 2
n2  n 2 n 

= R  2 − 2  , n = 4,3,4 = R  2 − 2  , n = 5,3,4
1 1 1 1 1 1
c) d)
n 3 n  n 4 n 
69. Mathematically Paschen series is represented as, where R is called Rydberg’s
constant:
 1 1 
= R  2 − 2  , n = 3,3,4
1 1 1 1
a) =R  − , n = 2,3,4 b)
n 1 2
n2  n 2 n 

= R  2 − 2  , n = 4,5,6 = R  2 − 2  , n = 5,3,4
1 1 1 1 1 1
c) d)
n 3 n  n 4 n 
70. Paschen series lies in:
a) Visible region b) Ultraviolet region c) Infrared region d) N.O.T
71. When an electron in hydrogen atom jumps from higher orbit into fourth orbit. The
set of lines emitted is called:
a) Balmer series b) Lyman series c) Bracket series d) Paschen series
72. When an electron in hydrogen atom jumps from higher orbit into second orbit. The
set of lines emitted is called:
a) Balmer series b) Lyman series c) Bracket series d) Paschen series
73. When an electron in hydrogen atom jumps from higher orbit into third orbit. The set
of lines emitted is called:
a) Balmer series b) Lyman series c) Bracket series d) Paschen series
74. When an electron jumps from the nth (higher orbit) orbit to the pth orbit (lower
orbit), the difference of energy is given by the equation:
a) hf = En - Ep b) hf = En + Ep c) hf = En d) hf = Ep - En
75. Whenever a hydrogen atom emits a photon in the Balmer series
(a) It need not emit any more photon
(b) It may emit another photon in the Pachen Series
(c) It must emit another photon in the Lyman Series
(d) It may emit another photon in the Balmer Series
76. In Bohr’s model of hydrogen atom, let PE represent potential energy and TE the total
energy. In going to a higher orbit,
(a) PE increase, TE decrease (b) PE decreases, TE increases
(b) PE increases, TE increases (d) PE decreases, TE decreases
77. As the quantum number increases, the difference energy between consecutive energy
levels :
(a) Decreases (b) increases
(c) First decreases and then increases (d) Remains same
78. The force acting on the electron in a hydrogen atom depends on the principle
quantum number as :
(a)
F ∝ n2 (b) F ∝ 1/n2 (c) F ∝ n4 (d) F ∝ 1/n4

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Test No. 18 ATOMIC SPECTRA /LINE SPECTRA

ANSWER KEY
1 C 21 B 41 C 61 B
2 A 22 B 42 C 62 B
3 C 23 C 43 A 63 A
4 D 24 C 44 C 64 A
5 B 25 A 45 C 65 A
6 A 26 B 46 B 66 A
7 C 27 B 47 C 67 B
8 C 28 C 48 B 68 A
9 B 29 D 49 B 69 C
10 B 30 B 50 A 70 C
11 C 31 D 51 A 71 C
12 B 32 B 52 C 72 A
13 E 33 B 53 C 73 D
14 A 34 A 54 D 74 A
15 A 35 D 55 B 75 C
16 A 36 C 56 E 76 B
17 B 37 D 57 B 77 A
18 A 38 B 58 A 78 D
19 C 39 C 59 A 79 --
20 B 40 B 60 C 80 ---

ENGR. KAMRAN ALI SOOMRO MCAT-2021