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Chemistry Atomic Structure Online Mcqs Test

Malik TahirLast Updated: October 14, 2025

Important Chemistry Atomic Structure Question and Answer

Total Questions:	86
Time Allowed:	40 Minutes
Total Marks:	86
How to Attempt Test:	Please choose the right Option in MCQ-type question.
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Chemistry Atomic Structure Practice Test Online With Explanation

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Page 1 of 86

Chemistry

1. Which of the air pressures is appropriate for the production of cathode rays in the discharge tube?

1 cm Hg

0.001 mm Hg

0.001 cm Hg

1 mm Hg

Page 2 of 86

2. Ionization energies of the elements of group A are greater than those of Group VI A. The reason is that

Group V A elements have greater shielding effect

Group V A elements half – filled atomic orbitals

Group V A element have less elector negativity

Group VI A elements have greater shielding effect

Page 3 of 86

3. When electron collide with heavy particles then which of the following is produced?

Gamma rays

Alpha rays

Beta rays

x-rays

Page 4 of 86

4. Positive rays give flash on

ZnS

AgCl plate

AgNO₃ plate

ZnO

Page 5 of 86

5. Pressure in gas discharge tube was kept

10 torr

0.1 torr

0.01 torr

1 torr

Page 6 of 86

6. Quantum number tells the energy of electron

Page 7 of 86

7. Ruther fords planet like structure was defective and unsatisfactory because

All

Moving e-accelerate towards the nucleus

Continuous spectrum

Behavior of electron remain unexplained

Page 8 of 86

8. The symbol of the element whose atoms have the outer most electronic configuration 2s² 2p³ is

Page 9 of 86

9. Total number of series in hydrogen spectrum is

Five

Six

Four

Three

Page 10 of 86

10. The mass of the atom is determined by

Electron

Electron and neutron

Neutrons

Neutron and proton

Page 11 of 86

11. The letters s p d and f are used to represent which quantum numbers

Spin

Azimuthal

Magnetic

Principal

Page 12 of 86

12. Photon of highest frequency will be absorbed when transition takes place from

3rd to 5th orbit

2nd to 5th orbit

1st to 5th orbit

4th to 5th orbit

Page 13 of 86

13. Charge of electron was measured by

Rutherford

Passim

J.J. Thomson

Millikan

Page 14 of 86

14. Choose the value of the Red berg’s constant among the following among the following

1.09678 x 10⁷ m¯¹

1.9678 x 10⁷ m¯¹

1.007 x 10⁷ m¯¹

1.697 x 10⁷ m¯¹

Page 15 of 86

15. The maximum number of electrons in a sub-shell for which l = 3 is

Page 16 of 86

16. The proton is heavier than an electron by

1850 times

1000 times

1840 times

100 times

Page 17 of 86

17. No two electrons is the same atom can have identical set of four quantum numbers. This statement is known as?

- Pauli’s Exclusion principle

- Aufbaus rule

- Hund’s rule

-(n + 1) rule

Page 18 of 86

18. When an atom absorbs energy the bonds in the spectrum will appeal which are

Hard to locate

Darker

Colourless

Brighter

Page 19 of 86

19. Which one is not true about cathode rays

Cannot ionized

9.11 x 10¯³¹ kg

Heat up

Cast shadow

Page 20 of 86

20. During a chemical reaction, atomic number

Changes and then is restored

Changed

Changes alternately

Remains same

Page 21 of 86

21. Plank’s theory says energy is emitted

Discontinuous manner

Never emit energy

In continuous manner

Simultaneously

Page 22 of 86

22. The penetrating power of X-rays depends on their

Source

Frequency

All of these

Applied voltage

Page 23 of 86

23. The value of e/m ratio of electron is

1.7588 x 10¹¹ C/kg

9.1095 x 10¯³¹ C/kg

1.7588 x 10²⁰ C/kg

6.02 x 10²³ C/kg

Page 24 of 86

24. Radiation emitted by exited atoms is

Nuclear radiations

Ultraviolet radiations

In the form of quanta

In the form of continuous waves

Page 25 of 86

25. e/m ratio of the canal rays is less than that of cathode rays. The reason is

Greater mass of canal ray particles

Actually e/m ratio of canal rays is greater than that of the cathode rays

Greater mass and charge of the canal ray particles

Greater charge of the canal ray particles

Page 26 of 86

26. Canal rays are

Negative charged particles

Gamma radiation

Positive charged particles

Beam of neutrons

Page 27 of 86

27. The credit of discovering neutron goes to

Austen

Langmuir

Rutherford

Chadwick

Page 28 of 86

28. Heaviest particle is

Meson

Proton

Electron

Neutron

Page 29 of 86

29. Wavelength of electron was verified by

Davison and Garner

Garter

Einstein

Moseley

Page 30 of 86

30. Planks theory says energy is emitted

Discontinuous manner

Simultaneously

In the form of heat

In continuous manner

Page 31 of 86

31. Subsidiary quantum number specifies

Nuclear stability

Orientations of orbital

Size of orbital

Shape of orbital

Page 32 of 86

32. The electronic configuration of an atom/ion can be defined by the following

Hund’s Rule

All the above

Pauli’s exclusion principle

Aufbau principle

Page 33 of 86

33. The number of neutrons in the element ⁹₄Be is

Page 34 of 86

34. At 200°C hydrogen molecules have velocity 10⁵ cm sec¯¹. The de-Broglie wavelength in this case is approximately

10 Å

1000 Å

100 Å

2 Å

Page 35 of 86

35. A 4f orbital has

One node

Two nodes

Four nodes

Three node

Page 36 of 86

36. An α-particle is

A proton

A Hydrogen nucleus

A Helium nucleus

An electron

Page 37 of 86

37. The relationship between energy of a photon of light and its frequency is given by

Bohr’s model

Plank’s quantum theory

Rutherford’s atomic model

De-Broglie’s dual nature of atom

Page 38 of 86

38. For which of the following sets of quantum numbers an electron will have the highest energy?

3, 2, 1, ½

4, 1, 0, -1/2

4, 2, -1, ½

5, 0, 0, ½

Page 39 of 86

39. The absolute charge of an electron is

+ 1.6 x 10¯¹⁹ C

-1.6 x 10¯¹⁹ C

1.6 x 10¯¹⁹ C

16 x 10¯¹⁹ C

Page 40 of 86

40. Particles are

Positive charged particles

Beam of neutrons

Negative charged particles

Gamma radiation

Page 41 of 86

41. Space around nucleus where finding of electrons is maximum is

Orbit

Sub shell

Electron cloud

Orbital

Page 42 of 86

42. When electron jump into orbit 1 then series obtained is

Paschen

Bracket

Lyman

P fund

Page 43 of 86

43. Positive particles in discharge tube is produced by ionization of gas molecules which is caused by

Gas molecules produce X – rays

Gas molecules are at high temperature

Gas molecules collide with anode

Cathode rays remove the electrons from gas molecules

Page 44 of 86

44. Hydrogen atom does not emit X-rays because

Its energy levels are too close to each other

It is too small in size

It has a single electron

Its energy levels are too far apart

Page 45 of 86

45. The electronic configuration of an atom is 2,8,3, The number of valence electrons in the atom is.

Page 46 of 86

46. Excited atoms return to their ground state in

10-9s

10-8s

10-10s

10-6s

Page 47 of 86

47. Millikan used in atomizer

Honey

H₂O

Milk

Oil

Page 48 of 86

48. Rutherford’s experiment led to the discovery of

Electron

α -particle

Nucleus

Proton

Page 49 of 86

49. Number of neutrons in heavy hydrogen atom is

Page 50 of 86

50. The radius of second Bohr’s orbit is

0.053/4 nm

0.053 nm

0.053 x 4 nm

0.053 x 20 nm

Page 51 of 86

51. X-ray are

Of unknown nature

High energy electrons

High energy photons

Radio isotopes

Page 52 of 86

52. An atom has a mass number of 23 and atomic number 11. The number of protons are

Page 53 of 86

53. A fast moving neutron can eject from nitrogen

X-rays

Β-rays

Electrons

r-rays

Page 54 of 86

54. The radius of hydrogen atom in the ground state is 0.53 Å, the radius of ₃Li²⁺ in the similar state is

0.53 Å

1.06 Å

0.265 Å

0.17 Å

Page 55 of 86

55. The mass of the neutron is of the order of

10¯²⁴ kg

10¯²³ kg

10¯²⁶ kg

10¯²⁷ kg

Page 56 of 86

56. When electrons revolve in stationary orbits,

There is increase in energy

There is no change in energy level

They are gaining kinetic energy

They become stationary

Page 57 of 86

57. The magnetic quantum number has value limited directly by the value of

Spin

Principal quantum number

Angular

Both a and b

Page 58 of 86

58. The letters S, P, d and f are used to represent which quantum number

Magnetic (m)

Spin (S)

Angular momentum (I)

Principal (p)

Page 59 of 86

59. In an X-ray tube electrons each of charge e are accelerated through V potential difference allowed to hit a metal target. The wavelength of the X-rays emitted is

he/ev

he/Ve

eV/h

Impossible to predict

Page 60 of 86

60. Mass number is equal to the

Number of protons + number of electrons

Number of protons + number of neutrons

Number of electrons

Number of neutrons + number of electrons

Page 61 of 86

61. Where does the cathode rays get deflected?

Both electric and magnetic field

An electric field only

A magnetic field only

None of these

Page 62 of 86

62. Rutherford’s gold foil experiment showed that most of the α particles passed through the gold foil without any deflection. It indicates that.

There is lot of empty space in atom

The nucleus carries positive charge

The nucleus carries the most of the mass

The nucleus is concentrated at the center

Page 63 of 86

63. P fund series are produced in the spectrum of hydrogen atom

When electrons jump down to 2nd – orbit

When electrons jump down to 5th – orbit

When electrons jump down to 4th – orbit

When electrons jump down to 3rd – orbit

Page 64 of 86

64. When X-rays are passed through successive aluminum sheets what happens to their thickness?

Sometimes increases and sometimes decreases

Increases

It decreases

It remains same

Page 65 of 86

65. Which of the following is not charged particles?

Hydrogen nucleus

Neutron

Proton

Electron

Page 66 of 86

66. The magnetic quantum number (QN) has its values determined directly by the value of

Principal (QN)

Both a and b

Azimuthal (QN)

Spin (QN)

Page 67 of 86

67. The number of spherical nodes in 3p orbitals are

One

Non

Three

Two

Page 68 of 86

68. The electron in an atom

Has fixed space around the nucleus

Moves around its nucleus in definite energy levels

Is stationary in various energy levels

Moves randomly around the nucleus

Page 69 of 86

69. Which one of the following will have the maximum charge/mass ratio?

Electron

Proton

Neutron

α particle

Page 70 of 86

70. In hydrogen spectrum which one of the following series lies in the ultraviolet region?

P fund series

Lymann series

Balmer series

Bracket series

Page 71 of 86

71. The quantum number which determines the shape of the orbital is

Principal

Spin

Azimuthal

Magnetic

Page 72 of 86

72. When atom is in the ground state, the electron is present

In the nucleus

Nearest to the nucleus

In the second shell

Nearest to the valence shell

Page 73 of 86

73. Millikan determined the charge on electron in oil drop experiment. It value is

1.603 x 10¯²³ C

6.625 x 10¯³⁴ C

1.602 x 10¯¹⁹ C

1.602 x 10¯²³ C

Page 74 of 86

74. The maximum number of electrons that can be accommodated by p – orbital is?

– 6

– 14

– 10

– 2

Page 75 of 86

75. The valence orbital configuration of an element with atomic number 23 is

3d³, 4s²

3d³, 4s¹, 4p¹

3d², 4s², 4p¹

3d⁵

Page 76 of 86

76. The K, L and M shells of an atom are full. Its atomic number is

Page 77 of 86

77. The total number of orbitals in a shell with principal quantum number ‘n’ is

n + 1

n²

2n²

Page 78 of 86

78. Almost the entire mass of an atom is concentrated in the

Neutrons

Proton

Nucleus

Electrons

Page 79 of 86

79. P fund series are produced in the spectrum of hydrogen atom

When electron jump to 2-orbit

When electron jump to 4-orbit

When electron jump to 3-orbit

When electron jump to 5-orbit

Page 80 of 86

80. If Z represents the atomic number and A represents mass number, then the number of electrons in an atom can be computed as

A + Z

A – Z

Z – A

Page 81 of 86

81. Rutherford’s atomic model suggests the existence of

α -particle

Atom

Nucleus

Mesons

Page 82 of 86

82. The number of electrons in the M shell of the element with atomic number 24 is

Page 83 of 86

83. The radiations emitted form hydrogen filled discharge tube show

Absorption spectrum

Continuous spectrum

Line spectrum

Band spectrum

Page 84 of 86

84. The mass of a neutron is times greater than the mass of electron

1840

1480

2000

540

Page 85 of 86

85. Spectrum is produced due to

Different wavelength

All have little contribution

Different colours

Different intensities

Page 86 of 86

86. The ratio of the ionization energy of H and Be³⁺ is

1 : 1

1 : 3

1 : 16

1 : 9

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Malik TahirLast Updated: October 14, 2025

4 Comments

Kamboh Rehan Kamboh says:

April 2, 2023 at 12:30 pm

I wanna mcqs of atomic structure

shoaib says:

February 7, 2022 at 10:12 pm

i want to practise on these questions

saeed ahmed says:

October 23, 2021 at 12:06 am

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Hizbullah Junejo says:

April 15, 2021 at 1:02 pm

I got 92%

Chemistry Atomic Structure Online Mcqs Test

Important Chemistry Atomic Structure Question and Answer

Chemistry Atomic Structure Practice Test Online With Explanation

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