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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. The mass of the atom is determined by

Electron and neutron

Electron

Neutron and proton

Neutrons

Page 2 of 86

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

Neutron

Electron

Proton

α particle

Page 3 of 86

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

Page 4 of 86

4. Charge of electron was measured by

Millikan

J.J. Thomson

Rutherford

Passim

Page 5 of 86

5. An α-particle is

A proton

A Hydrogen nucleus

A Helium nucleus

An electron

Page 6 of 86

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

Gas molecules collide with anode

Cathode rays remove the electrons from gas molecules

Gas molecules produce X – rays

Gas molecules are at high temperature

Page 7 of 86

7. Excited atoms return to their ground state in

10-8s

10-9s

10-10s

10-6s

Page 8 of 86

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

Aufbau principle

Hund’s Rule

Pauli’s exclusion principle

All the above

Page 9 of 86

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

Spin

Azimuthal

Magnetic

Principal

Page 10 of 86

10. Wavelength of electron was verified by

Garter

Davison and Garner

Moseley

Einstein

Page 11 of 86

11. Heaviest particle is

Proton

Neutron

Electron

Meson

Page 12 of 86

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

2n²

n + 1

n²

Page 13 of 86

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

0.17 Å

0.265 Å

0.53 Å

1.06 Å

Page 14 of 86

14. X-ray are

Of unknown nature

High energy electrons

High energy photons

Radio isotopes

Page 15 of 86

15. Spectrum is produced due to

Different intensities

Different colours

All have little contribution

Different wavelength

Page 16 of 86

16. During a chemical reaction, atomic number

Changes and then is restored

Changed

Remains same

Changes alternately

Page 17 of 86

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

Principal

Spin

Azimuthal

Magnetic

Page 18 of 86

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

1.7588 x 10¹¹ C/kg

1.7588 x 10²⁰ C/kg

6.02 x 10²³ C/kg

9.1095 x 10¯³¹ C/kg

Page 19 of 86

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

10¯²³ kg

10¯²⁷ kg

10¯²⁴ kg

10¯²⁶ kg

Page 20 of 86

20. Mass number is equal to the

Number of protons + number of neutrons

Number of neutrons + number of electrons

Number of protons + number of electrons

Number of electrons

Page 21 of 86

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

1000 Å

10 Å

2 Å

100 Å

Page 22 of 86

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

Bohr’s model

Rutherford’s atomic model

Plank’s quantum theory

De-Broglie’s dual nature of atom

Page 23 of 86

23. Pressure in gas discharge tube was kept

1 torr

0.1 torr

0.01 torr

10 torr

Page 24 of 86

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

Page 25 of 86

25. A 4f orbital has

Four nodes

Three node

Two nodes

One node

Page 26 of 86

26. Where does the cathode rays get deflected?

A magnetic field only

Both electric and magnetic field

An electric field only

None of these

Page 27 of 86

27. A fast moving neutron can eject from nitrogen

r-rays

Electrons

X-rays

Β-rays

Page 28 of 86

28. Canal rays are

Gamma radiation

Positive charged particles

Negative charged particles

Beam of neutrons

Page 29 of 86

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

It decreases

It remains same

Increases

Sometimes increases and sometimes decreases

Page 30 of 86

30. The credit of discovering neutron goes to

Langmuir

Austen

Rutherford

Chadwick

Page 31 of 86

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

Beta rays

Gamma rays

x-rays

Alpha rays

Page 32 of 86

32. Particles are

Gamma radiation

Beam of neutrons

Negative charged particles

Positive charged particles

Page 33 of 86

33. The absolute charge of an electron is

-1.6 x 10¯¹⁹ C

1.6 x 10¯¹⁹ C

16 x 10¯¹⁹ C

+ 1.6 x 10¯¹⁹ C

Page 34 of 86

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

Spin

Principal quantum number

Angular

Both a and b

Page 35 of 86

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

0.001 mm Hg

1 cm Hg

0.001 cm Hg

1 mm Hg

Page 36 of 86

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

Principal (QN)

Spin (QN)

Both a and b

Azimuthal (QN)

Page 37 of 86

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

Lyman

Bracket

P fund

Paschen

Page 38 of 86

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

1.602 x 10¯²³ C

6.625 x 10¯³⁴ C

1.603 x 10¯²³ C

1.602 x 10¯¹⁹ C

Page 39 of 86

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

The nucleus carries the most of the mass

The nucleus is concentrated at the center

The nucleus carries positive charge

There is lot of empty space in atom

Page 40 of 86

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

Page 41 of 86

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

4th to 5th orbit

1st to 5th orbit

2nd to 5th orbit

3rd to 5th orbit

Page 42 of 86

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

Magnetic (m)

Spin (S)

Angular momentum (I)

Principal (p)

Page 43 of 86

43. When electrons revolve in stationary orbits,

There is increase in energy

They are gaining kinetic energy

They become stationary

There is no change in energy level

Page 44 of 86

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

P fund series

Balmer series

Bracket series

Lymann series

Page 45 of 86

45. Positive rays give flash on

ZnO

ZnS

AgCl plate

AgNO₃ plate

Page 46 of 86

46. Planks theory says energy is emitted

Simultaneously

Discontinuous manner

In the form of heat

In continuous manner

Page 47 of 86

47. Rutherford’s experiment led to the discovery of

Proton

Nucleus

α -particle

Electron

Page 48 of 86

48. The radiations emitted form hydrogen filled discharge tube show

Continuous spectrum

Line spectrum

Band spectrum

Absorption spectrum

Page 49 of 86

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

Electrons

Nucleus

Neutrons

Proton

Page 50 of 86

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

Brighter

Colourless

Hard to locate

Darker

Page 51 of 86

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

Applied voltage

Source

Frequency

All of these

Page 52 of 86

52. Subsidiary quantum number specifies

Nuclear stability

Orientations of orbital

Shape of orbital

Size of orbital

Page 53 of 86

53. 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

-(n + 1) rule

- Hund’s rule

Page 54 of 86

54. Which one is not true about cathode rays

9.11 x 10¯³¹ kg

Heat up

Cannot ionized

Cast shadow

Page 55 of 86

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

When electrons jump down to 4th – orbit

When electrons jump down to 3rd – orbit

When electrons jump down to 5th – orbit

When electrons jump down to 2nd – orbit

Page 56 of 86

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

Group V A elements half – filled atomic orbitals

Group V A element have less elector negativity

Group VI A elements have greater shielding effect

Group V A elements have greater shielding effect

Page 57 of 86

57. Radiation emitted by exited atoms is

Ultraviolet radiations

Nuclear radiations

In the form of continuous waves

In the form of quanta

Page 58 of 86

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

– 6

– 14

– 2

– 10

Page 59 of 86

59. Number of neutrons in heavy hydrogen atom is

Page 60 of 86

60. Which of the following is not charged particles?

Hydrogen nucleus

Proton

Neutron

Electron

Page 61 of 86

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

Three

Non

Two

One

Page 62 of 86

62. The proton is heavier than an electron by

100 times

1850 times

1840 times

1000 times

Page 63 of 86

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

4, 1, 0, -1/2

5, 0, 0, ½

4, 2, -1, ½

3, 2, 1, ½

Page 64 of 86

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

Page 65 of 86

65. Hydrogen atom does not emit X-rays because

Its energy levels are too close to each other

It has a single electron

Its energy levels are too far apart

It is too small in size

Page 66 of 86

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

Page 67 of 86

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

1480

1840

540

2000

Page 68 of 86

68. Quantum number tells the energy of electron

Page 69 of 86

69. Plank’s theory says energy is emitted

In continuous manner

Discontinuous manner

Simultaneously

Never emit energy

Page 70 of 86

70. Millikan used in atomizer

Milk

H₂O

Honey

Oil

Page 71 of 86

71. 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

eV/h

he/Ve

he/ev

Impossible to predict

Page 72 of 86

72. The electron in an atom

Has fixed space around the nucleus

Moves randomly around the nucleus

Moves around its nucleus in definite energy levels

Is stationary in various energy levels

Page 73 of 86

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

Page 74 of 86

74. The radius of second Bohr’s orbit is

0.053 nm

0.053 x 4 nm

0.053/4 nm

0.053 x 20 nm

Page 75 of 86

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

When electron jump to 5-orbit

When electron jump to 2-orbit

When electron jump to 3-orbit

When electron jump to 4-orbit

Page 76 of 86

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

Greater charge of the 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 mass of canal ray particles

Page 77 of 86

77. Rutherford’s atomic model suggests the existence of

Atom

α -particle

Mesons

Nucleus

Page 78 of 86

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

Page 79 of 86

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

3d³, 4s¹, 4p¹

3d³, 4s²

3d², 4s², 4p¹

3d⁵

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

Z – A

A – Z

Page 81 of 86

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

1.09678 x 10⁷ m¯¹

1.007 x 10⁷ m¯¹

1.9678 x 10⁷ m¯¹

1.697 x 10⁷ m¯¹

Page 82 of 86

82. Total number of series in hydrogen spectrum is

Six

Three

Five

Four

Page 83 of 86

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

Moving e-accelerate towards the nucleus

All

Behavior of electron remain unexplained

Continuous spectrum

Page 84 of 86

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

Orbital

Orbit

Sub shell

Electron cloud

Page 85 of 86

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

In the second shell

Nearest to the nucleus

Nearest to the valence shell

In the nucleus

Page 86 of 86

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

1 : 16

1 : 9

1 : 1

1 : 3

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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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