ATOMIC PHYSICS

1. When a α-particle of mass ‘m’ moving with velocity ‘v’ bombards on a heavy nucleus of
charge ‘Ze’. It distance of closest approach from the nucleus depends on m as:

a) 1/m
b) 1/√m
c) 1/m2
d) m

2. an alpha nucleus energy ( ½ mv2 ) bombards a heavy nuclear target of charge Ze. Then the
distance of closest approach for the alpha nucleus will be proportional to

a) 1/Ze
b) V2
c) 1/m
d) 1/v4

3. In Rutherford scattering what will be the correct angle for α-scattering for an impact
parameter, b = 0?

a) 90 degree
@

b) 270 degree
c) 0 degree
ab

d) 180 degree
hi

4.
_1
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5. In terms of Bohr radius the radius ao the second Bohr orbit of a hydrogen atom is given by

a) 4ao
b) 8ao
c) √2ao
d) 2ao

6. When hydrogen atom is in its first excited level. Its radius is……….of the Bohr radius.

a) Twice

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 ATOMIC PHYSICS

b) 4 times
c) Same
d) Half

7. What should be the angular momentum of an electron in Bhor’s hydrogen atom whose
energy is -0.544 eV?

a) h/ π
b) 3h/2 π
c) 5h/2 π
d) 2h/2 π

8. The speed of an electron in the 4th orbit of hydrogen atom is

a) c
b) c/137
c) c/2192
d) c/548

9.
@
ab
hi
_1
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10. Ratio of longest wavelengths corresponding to lyman and Balmer series in hydrogen
spectrum is

a) 7/29
b) 9/31
c) 5/27
d) 5/23

11. The energies of three conservative energy levels L3 , L2 , L1 of hydrogen atom are Eo, 4Eo/9
and Eo /4 respectively. A photon of wavelength λ is emitted for a transition L3 to L1. What will
be the wavelength of emission for transition L2 to L1 .

a) 16 λ/31
b) 27 λ/7
c) 19 λ/20
d) λ

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 ATOMIC PHYSICS

12.

13.

14.
@
ab
hi

15. With the help of Rydberg formula find the wavelength of first line of P fund series
16.
_1
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17.

18.

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 ATOMIC PHYSICS

19.

20.

21.
@
ab
hi

22.
_1
8 63

23.

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 ATOMIC PHYSICS

24.

25.

26.
@
ab

27.
hi
_1
8 63

28.

29.

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 ATOMIC PHYSICS

30.

31. The ground state energy of H – atom is -13.6 ev. The energy needed to ionise H – atom from
its second excited state is

a) 1.51 eV
b) 3.4eV
c) 13.6 eV
d) 12.1 eV

32. The angular speed of electron in the nth orbit of hydrogen atom is

a) Directly proportional to n2
b) Directly proportional to n
c) Inversely proportional to n3
@

d) Inversely proportional to n
ab

33. Of the various series of the hydrogen spectrum, the one which lies completely in the
ultraviolet region is
hi

a) Lyman series
_1

b) Balmer series
c) Paschen series
8

d) Bracket series
63

34. As the n ( number of orbit) increases, the difference of energy between the consecutive
energy levels

a) Remains the same

b) Increase
c) Decrease
d) Sometimes increase and sometimes decrease

35. The ratio of minimum to maximum wavelength of radiation limited by transition of an

electron to ground state of bohr’s hydrogen atom is

a) 3/4
b) 1/4
c) 1/8
d) 1/8

36. In Bohr’s model of the hydrogen atom the ratio between the period of revolution of an
electron in the orbit of n = 1 to the period of revolution of the electron in the orbit n = 2 is

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 ATOMIC PHYSICS

a) 1:2
b) 2:1
c) 1:4
d) 1:8

37. ow many times does the electron go round the first bohr orbit in a second

a) 6.57 * 105
b) 6.57 * 1010
c) 6.57 * 1013
d) 6.57 * 1015

38. The ratio of the energies of the hydrogen atom in its first excited state to 2nd excited state is

a) 1/4
b) 4/9
c) 9/4
d) 4

39. Which of the following transition hydrogen atom emit photons of lowest frequency
@

a) n = 2 to n= 1
ab

b) n = 4 to n = 2
c) n = 4 to n = 3
hi

d) n = 3 to n = 1
_1

40. The energy of hydrogen atom in its ground state is -136. eV. The energy of the level
corresponding to n = 5 is
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a) -0.544 eV
b) -5.40 eV
c) -0.85 eV
d) -2.72 eV

41. If the electron is hydrogen atom jump from 3rd orbit to second orbit the wavelength of the
immediate radiation is given by

a) λ = 36/5R
b) λ = 5R/36
c) λ = 5/R
d) λ = R/6

42. The total energy of an electron in the hydrogen atom in the Ground state is -13.6 . The
kinetic energy of this electron is

a) 13.6 eV
b) 0
c) -13.6 eV

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 ATOMIC PHYSICS

d) 6.8 eV

43. The wavelength of first member of Balmer series in hydrogen spectrum is λ. Calculated the
wavelength of first member of Lyman series in the same spectrum

a) (5/27) λ
b) (4/27) λ
c) (27/5) λ
d) (27/4) λ

44. Which state of triply ionised beryllium ( Be3+ ) has the same orbital radius as that of the
ground state of hydrogen

a) 1
b) 2
c) 3
d) 4

45. Electron makes a transition from orbit n = 4 to the orbit n = 2 of a hydrogen atom. Which is
the wavelength of the emitted radiations? ( R = Rydberg’s constant)
@

a) 16/4R
ab

b) 16/5R
c) 16/2R
hi

d) 16/3R
_1

46. Compton effect support that

8

a) X rays are transverse wave

63

b) X ray have high frequency compared to visible light

c) X ray can easily penetrate matter
d) Photons have momentum

47. Which is the correct relation between de-Broglie wavelength of an electron in the nth bohr
orbit and radius of the orbit R?

48. Hydrogen items are excited from ground State to the Principle quantum number 5 number
of spectral line observed will be

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 ATOMIC PHYSICS

a) 5
b) 4
c) 10
d) 8

49. If in Bohr’s atomic model, it is assumed that force between electron and proton varies
inversely as r4 , energy of the system will be proportional to

a) n2
b) n4
c) n6
d) n8

50. What should be the ratio of minimum to maximum wavelength of radiation emitted by
transition of an electron to ground State of bohr’ hydrogen atom

a) ¾
b) ¼
c) 1/8
d) 3/8
@

51. The product of angular speed and tangential speed of electron in nth orbit of hydrogen atom
ab

is
hi

a) Directly proportional to n2
_1

b) Directly proportional to n3
c) inversely proportional to n4
d) independent of n
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52. when an electron do transition from n = 4 to n = 2, then emitted line in spectrum will be

a) 1st line of Lyman series

b) 2nd line of Balmer series
c) 1st line of Paschen series
d) 2nd line of Paschen series

53. The energy of hydrogen atom in nth orbit is En then the energy in nth orbit of singly ionised
helium atom will be

a) 4 En
b) En /4
c) 2 En
d) En /2

54. In each of the following system will the radius of the first orbit ( n = 1) be minimum

a) Doubly ionized lithium

b) Singly ionized helium

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 ATOMIC PHYSICS

c) Deuterium atom
d) Hydrogen atom

55. Assuming Bohr’s model for Li++ atom the first excitation energy of ground state Li ++ atom is

a) 10.2 eV
b) 91.8 eV
c) 13.6 eV
d) 3.4 eV

56. The absorption transition between the first and the 4th energy states of hydrogen atom are 3
the emission transition between these state will be

a) 3
b) 4
c) 5
d) 6

57. When a hydrogen atom emits a photon of energy 12.1 eV, Its orbital angular momentum
changes by ( where h is Planck’s constant)
@

a) 3h/π
ab

b) 2h/ π
c) h/ π
hi

d) 4h/ π
_1

58. Which of the following is /are possible values of radius of stable orbit of hydrogen atom
8

a) λ /2π
63

b) 3λ /4π
c) λ /π
d) 5λ /4π

59. The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is

a) 1
b) 4
c) 0.5
d) 2

60. Given the value of Rydberg constant is107 m-1 the wave number of the last line of the Balmer
series in hydrogen spectrum will be

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 ATOMIC PHYSICS

61. Ratio of longest wavelengths corresponding to Lyman and Balmer series in hydrogen
spectrum is

a) 7/29
b) 9/31
c) 5/27
d) 5/23

62. The energy of a hydrogen atom in the ground state is -13.6 eV. The energy of a He+ ion in
the first state will be
@

a) -13.6 eV
ab

b) -27.2 eV
c) -54.4 eV
d) -6.8 eV
hi
_1

63. The electron in the hydrogen atom jumps from excited state ( n= 3) to its ground state ( n =
1) and the photons thus emitted irradiate a photosensitive material. If the work function of
8

the material is 5.1 eV, the stopping potential is estimated to be ( the energy of the electron
in nth state En = -13.6 / n2 eV)
63

a) 5.1 V
b) 12.1 V
c) 17.2 V
d) 7V

64. Consider 3rd orbit of He+ ( helium) using non-relativistic approach, the speed of electron in
this orbit will be [ given K = 9 * 109 constant Z = 2 and h ( Planck’s constant ) = 6.6 * 10-34 j s]

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 ATOMIC PHYSICS

65. In which of the following system will the radius of the orbit ( n = 1) be minimum?

a) Doubly ionized lithium

b) Single ionized lithium
c) Deuterium atom
d) Hydrogen atom

66. If an electron in a hydrogen atom jumps from the 3rd orbit to 2nd orbit, it emits a photon of
wavelength λ. When it jumps from the 4th orbit to the 3rd orbit, the corresponding
wavelength of the photon will be

a) 16/25 λ
b) 9/16 λ
c) 20/7 λ
d) 20/13 λ

67. Hydrogen atom in ground state is excited by a monochromatic radiation of λ = 975 A.

number of spectral lines in the resulting spectrum emitted will be

a) 3
@

b) 2
c) 6
ab

d) 10
hi
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