# Class 10 Physics Chapter 9

Updated: 21 Dec 2023

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Class 10 Physics Chapter 9 introduces the concept of “Radioactivity”. This is mainly chapter No. 18, “Radioactivity”, of the book of Class 10.
This article consists of Notes, SLO Based Notes and MCQs of Physics, which cover your course, board papers and clear your Physics concept for different types of tests.

## Class 10 Physics Chapter 9 Notes

Class 10 Physics Chapter No. 18 Notes

### SLO Base Notes

Class 10 Physics Chapter 18 SLO Base Notes

## Class 10 Physics Chapter 9 MCQs

1. This field focuses on understanding the properties, structure, and interactions of atomic nuclei, including the study of nuclear reactions and nuclear forces is:
(a) Nuclear Physics
(b) Quantum Physics
(c) Astrophysics
(d) Thermodynamics

Nuclear Physics

2. What is the central, positively charged core of an atom called?
(a) Electron
(b) Nucleus
(c) Neutron
(d) Proton

Nucleus

3. The nucleus is about how many times smaller than the atom?
(a) 100 times
(b) 1,000 times
(c) 10,000 times
(d) 100,000 times

10,000 times

4. What force is responsible for keeping the positively charged protons within the atomic nucleus?
(a) Electromagnetic force
(b) Gravitational force
(c) Nuclear force
(d) Electrostatic force

Nuclear force

5. Which term is used to describe atoms of the same element with the same number of protons but different numbers of neutrons?
(a) Isotopes
(b) Nuclides
(c) Molecules
(d) Compounds

Isotopes

6. What fraction of the atom’s volume does the nucleus occupy?
(a) \frac{1}{2}

(b) \frac{.1}{10}

(c) \frac{1}{100}

(d) \frac{1}{10^{15}}

\frac{1}{10^{15}}

7. The nucleus is composed of:
(a) Electrons and protons
(b) Protons and neutrons
(c) Electrons and neutrons
(d) Positrons and electrons

Protons and neutrons

8. Which particle is present in the ordinary hydrogen nucleus?
(a) Proton
(b) Neutron
(c) Electron
(d) Positron

Proton

9. What term is used to collectively refer to protons and neutrons in a nucleus?
(a) Electrons
(b) Quarks
(c) Nucleons
(d) Leptons

Nucleons

10. How many protons are present in the ordinary hydrogen nucleus?
(a) 0
(b) 1
(c) 2
(d) 3

1

11. Which nucleus is an exception to the presence of both protons and neutrons?
(a) Helium nucleus
(b) Oxygen nucleus
(c) Hydrogen nucleus
(d) Carbon nucleus

Hydrogen nucleus

12. What does the atomic number, Z, represent in an atom?
(a) Number of positron
(b) Number of protons
(c) Total nucleons
(d) Mass number

Number of protons

13. The nucleon (or mass) number, A, is the sum of:
(a) Electrons and protons
(b) Protons and neutrons
(c) Neutrons and electrons
(d) Protons, neutrons, and electrons

Protons and neutrons

14. How is the neutron number, N, calculated?
(a) N = Z – A
(b) N = A + Z
(c) N = A – Z
(d) N = \frac{Z}{A}

N = A – Z

15. If an atom has a mass number (A) of 25 and an atomic number (Z) of 10, what is the neutron number (N) ?
(a) 15
(b) 25
(c) 10
(d) 5

15

16. In an atom with Z = 8 \ and \ N = 10 , what is the mass number (A) ?
(a) 18
(b) 2
(c) 8
(d) 16

18

17. If the neutron number (N) in an atom is 20 and the mass number (A) is 40, what is the atomic number (Z)?
(a) 60
(b) 20
(c) 40
(d) 80

20

18. The spontaneous release of subatomic particles by unstable atoms is called:
(a) Nuclear fusion
(b) Nucleus disintegration
(c) Subatomic decay

19. Which type of radiation involves the emission of He-4 nuclei?
(d) None of these

20. An element with unstable nuclei undergoing spontaneous decay is said to be:
(b) Stable element
(c) Decay element

21. What are the three types of radiation emitted during radioactive decay?
(a) Delta, epsilon, zeta
(b) Alpha, beta, gamma
(c) Sigma, pi, rho
(d) Mu, nu, tau

Alpha, beta, gamma

(d) None of these

23. What are nuclei termed that do not emit radiations?
(b) Stable nuclei
(c) Inert nuclei
(d) Active nuclei

Stable nuclei

24. In a magnetic field, which radiation is not deflected?
(a) Alpha (\alpha) rays
(b) Beta (\beta) rays
(c) Gamma (\gamma) rays
(d) None of these

Gamma (\gamma) rays

25. In the presence of a magnetic field, the not deflected radiation carries:
(a) Positive charge
(b) Negative charge
(c) Variable charge
(d) No charge

No charge

26. The component of radiation experiencing no change in direction in an electric field is:
(a) Alpha (\alpha) rays
(b) Beta (\beta) rays
(c) Gamma (\gamma) rays
(d) None of these

Gamma (\gamma) rays

27. The component of radiation deflecting towards the positive plate in an electric field is:
(a) Alpha (\alpha) rays
(b) Beta (\beta) rays
(c) Gamma (\gamma) rays
(d) None of these

Beta (\beta) rays

28. The component of radiation deflecting towards the negative plate in an electric field is:
(a) Alpha (\alpha) rays
(b) Beta (\beta) rays
(c) Gamma (\gamma) rays
(d) None of these

Alpha (\alpha) rays

(a) With a defined pattern
(b) Randomly
(c) Predictably
(d) Controllably

Randomly

30. What is the composition of Alpha (\alpha) particles?
(a) Protons only
(b) Neutrons only
(c) 2 protons and 2 neutrons
(d) Electrons only

2 protons and 2 neutrons

31. Under what condition do certain atoms emit alpha particles?
(a) High neutron-to-proton ratio
(b) Low neutron-to-proton ratio
(c) Balanced neutron-to-proton ratio
(d) No specific condition

Low neutron-to-proton ratio

32. What is the composition of beta (\beta) particles?
(a) Protons only
(b) Neutrons only
(c) Electrons
(d) Protons and electrons together

Electrons

33. When does beta particle emission occur?
(a) High neutron-to-proton ratio
(b) Low neutron-to-proton ratio
(c) Stable neutron-to-proton ratio
(d) High proton-to-neutron ratio

High neutron-to-proton ratio

34. What type of radiation is gamma (\gamma) emission?
(b) Particle emission
(c) Proton emission
(d) Neutron emission

35. When does gamma ray emission occur?
(a) Low energy in the nucleus
(b) High energy in the nucleus
(c) Balanced energy in the nucleus
(d) No specific energy condition

High energy in the nucleus

36. What is the composition of gamma (\gamma) radiation?
(a) Electrons
(b) 2 protons and 2 neutrons
(d) Protons only

37. What is the charge of alpha (\alpha) particles?
(a) +1
(b) +2
(c) -1
(d) 0

+2

38. What is the charge of beta (\beta) particles?
(a) +1
(b) +2
(c) -1
(d) 0

-1

39. What is the charge of gamma (\gamma) radiation?
(a) +1
(b) +2
(c) -1
(d) 0

0

40. What effect does alpha (\alpha) radiation have on the parent nucleus?
(a) Energy loss
(b) Mass loss: new element produced
(c) No change in mass: new element produced
(d) Neutron emission

Mass loss: new element produced

41. What effect does beta (\beta) radiation have on the parent nucleus?
(a) Energy loss
(b) Mass loss: new element produced
(c) No change in mass: new element produced
(d) Proton emission

No change in mass: new element produced

42. What effect does gamma (\gamma) radiation have on the parent nucleus?
(a) Energy loss
(b) Mass loss: new element produced
(c) No change in mass: new element produced
(d) Neutron emission

Energy loss

43. What is ionization in term of radiation?
(b) Splitting matter into positive and negative ions
(c) Penetration into materials

Splitting matter into positive and negative ions

44. Which radiation type has the strongest ionizing ability in air?
(a) Alpha (\alpha) particles
(b) Beta (\beta) particles
(c) Gamma (\gamma) rays
(d) None of these

Alpha (\alpha) particles

45. Which radiation type has the least ionizing ability in air?
(a) Alpha (\alpha) particles
(b) Beta (\beta) particles
(c) Gamma (\gamma) rays
(d) None of these

Gamma (\gamma) rays

46. Which radiation type has the strongest penetrating ability in air?
(a) Alpha (\alpha) particles
(b) Beta (\beta) particles
(c) Gamma (\gamma) rays
(d) None of these

Gamma (\gamma) rays

47. Which radiation type has the least penetrating ability in air?
(a) Alpha (\alpha) particles
(b) Beta (\beta) particles
(c) Gamma (\gamma) rays
(d) None of these

Alpha (\alpha) particles

48. How many known nuclides are considered stable among approximately 3000?
(a) 100
(b) 257
(c) 500
(d) 1000

257

49. What is the term for the process in which an unstable nucleus transforms into a more stable nucleus?
(a) Nuclear fission
(b) Nuclear fusion
(c) Nuclear transmutation
(d) None of these

Nuclear transmutation

50. In nuclear transmutations, what is the original element called?
(a) Daughter
(b) Parent
(d) Unstable

Parent

51. What is the newly formed element termed as in nuclear transmutations?
(a) Daughter
(b) Parent
(c) Unstable
(d) None of these

Daughter

52. How does the nucleon number change in the daughter nuclide compared to the parent nuclide in alpha decay?
(a) Reduced by one
(b) Reduced by two
(c) Reduced by three
(d) Reduced by four

Reduced by four

53. What happens to the charge of the daughter nuclide in alpha decay?
(a) No change
(b) Increased by one
(c) Reduced by one
(d) Reduced by two

Reduced by two

54. Find the daughter nucleus when Radium-224 undergoes alpha decay.
(b) Polonium-210
(d) Thorium-230

55. In beta decay, what particle is emitted to transform the original nuclide into a daughter nuclide?
(a) Alpha particle
(b) Beta particle
(c) Gamma ray
(d) Neutron

Beta particle

56. Find the daughter nucleus when Carbon-14 undergoes beta decay.
(a) Nitrogen-14
(b) Oxygen-14
(c) Nitrogen-13
(d) Oxygen-13

Nitrogen-14

57. In gamma decay, what type of radiation is emitted for achieving further stability?
(a) Alpha particles
(b) Beta particles
(c) Gamma rays
(d) Neutrons

Gamma rays

58. How do nuclei achieve further stability after alpha or beta emission?
(a) By absorbing gamma rays
(b) By emitting alpha particles
(c) By emitting gamma rays
(d) By undergoing fission

By emitting gamma rays

59. Approximately, how many decays per second does one curie (Ci) represent?
(a) 1
(b) 3.70 \times 10^{10}
(c) 10
(d) 1 \times 10^6

3.70 \times 10^{10}

60. What is the SI unit of activity, defined as one decay per one second?
(a) Curie (Ci)
(b) Becquerel (Bq)
(c) Rutherford (Rd)
(d) None of these

Becquerel (Bq)

61. How many Becquerels (Bq) are equivalent to 1 curie (Ci)?
(a) 1
(b) 3.70 \times 10^{10}
(c) 10
(d) 1 \times 10^6

3.70 \times 10^{10}

62. What are the names of the two radioactive elements discovered by the Curies?
(a) Uranium and Thorium
(d) Neptunium and Plutonium

63. The time for half of the radioactive nuclei to decay is;
(a) Decay period
(c) Half-life
(d) Nuclei duration

Half-life

64. What happens to the probability of decay for a given nucleus over time?
(a) It decreases
(b) It increases
(c) It remains constant
(d) It becomes zero

It remains constant

65. How does the amount of radioactive isotope in a sample change with time?
(a) It remains constant
(b) It increases
(c) It decreases
(d) It becomes inert

It decreases

66. The quantity of a radioactive substance is reduced to 1/8^{th} of its initial amount. How many half-lives have elapsed?
(a) 2
(b) 3
(c) 4
(d) 5

3

67. If a radioactive substance has a half-life of 10 days, what percentage of the substance will remain after 30 days?
(a) 12.5 \%
(b) 25 \%
(c) 50 \%
(d) 75 \%

12.5 \%

68. If the half-life of a radioactive substance is 2 hours, how much of the substance will remain after 8 hours?
(a) \frac{1}{8}
(b) \frac{1}{16}
(c) \frac{1}{4}
(d) \frac{1}{2}

1/16

69. The isotopes that are unstable and emit radiations are called;
(b) Stable isotopes
(c) Isotopes
(d) Inert isotopes

70. Which of the following is an example of a natural isotope of carbon?
(a) Carbon-12
(b) Carbon-13
(c) Carbon-14
(d) All of these

All of these

71. Which carbon isotope is considered the most stable artificial isotope?
(a) Carbon-12
(b) Carbon-13
(c) Carbon-14
(d) Carbon-11

Carbon-11

72. What percentage of carbon as found in nature consists of the C-12 isotope?
(a) 1.11 \%
(b) 5.700 \%
(c) 2 0.334 \%
(d) 98.89 \%

98.89 \%

73. What is the half-life of the C-14 isotope of carbon?
(a) 20.334 minutes
(b) 5,700 years
(c) 200 milliseconds
(d) 20 seconds

5,700 years

74. How many isotopes does carbon have in total?
(a) 10
(b) 15
(c) 20
(d) 25

15

75. How many stable isotopes do most elements typically have?
(a) Between 1 and 2
(b) Between 2 and 6
(c) Between 6 and 10
(d) More than 10

Between 2 and 6

76. How many stable isotopes does tin have?
(a) 5
(b) 8
(c) 10
(d) 15

10

77. What is the half-life of the most stable artificial radioisotope of carbon?
(a) 20.334 minutes
(b) 5,700 years
(c) Less than 20 seconds
(d) More than 200 milliseconds

20.334 minutes

78. What distinguishes Carbon-14 from other radioisotopes of carbon?
(a) Longer half-life
(b) Shorter half-life
(d) Higher atomic number

Longer half-life

79. What is the purpose of food irradiation using gamma rays?
(a) Enhance taste
(b) Increase nutritional content
(c) Kill bacteria and molds
(d) Shorten shelf life

Kill bacteria and molds

80. What is the primary benefit of using gamma rays to sterilize hospital equipment?
(a) Heating the equipment
(b) Minimizing damage to sensitive items
(c) Enhancing equipment durability
(d) None of these

Minimizing damage to sensitive items

81. What is the primary purpose of using radiopharmaceuticals in medical diagnostics?
(a) Enhancing physical fitness
(b) Stimulating hormone production
(c) Imaging internal organs
(d) Treating bacterial infections

Imaging internal organs

82. Why is it essential for a radioisotope used in medical diagnosis to have a short half-life?
(a) To ensure prolonged imaging
(c) To enhance therapeutic effects
(d) To increase gamma ray emission

83. What type of radiation does Cobalt-60 emit, making it suitable for treating various cancers?
(a) Alpha particles
(b) Beta particles and gamma rays
(c) Gamma rays only
(d) Neutrons

Beta particles and gamma rays

84. What is the primary material used for radioactive dating by archaeologists and geologists?
(a) Uranium-238
(b) Cobalt-60
(c) Carbon-11
(d) Iodine-131

Uranium-238

85. Who discovered nuclear fission in December 17, 1938?
(a) Marie Curie
(b) Otto Hahn and Fritz Strassmann
(c) Lise Meitner
(d) Albert Einstein

Otto Hahn and Fritz Strassmann

86. The process of splitting of nuclei into intermediate size nuclei is called:
(a) Nuclear Fusion
(b) Nuclear Decay
(c) Nuclear Fission
(d) Nuclear Transmutation

Nuclear Fission

87. What is the result of the nuclear fission process?
(a) Formation of alpha particles
(b) Production of free neutrons and gamma rays
(c) Generation of protons and electrons
(d) Emission of visible light

Production of free neutrons and gamma rays

88. What are the resulting nuclei X and Y called in the fission process?
(a) Fission byproducts
(b) Fusion fragments
(c) Neutron emitters
(d) Fission fragments

Fission fragments

89. How many average numbers of neutrons are typically released per event in nuclear fission reaction?
(a) 1 neutron
(b) 2 neutrons
(c) 3 neutrons
(d) 2.5 neutrons

2.5 neutrons

90. In nuclear fission, the intermediate excited state that lasts for _________ before splitting into X and Y.
(a) 1 nano-seconds
(b) 1 micro-seconds
(c) 1 milli-seconds
(d) 1 pico-seconds

1 pico-seconds

91. The energy release from 1 kg of uranium compared to the energy released from:
(a) 100 tons of coal
(b) 1000 tons of coal
(c) 3000 tons of coal
(d) 5000 tons of coal

3000 tons of coal

92. When one nuclear reaction causes an average of one or more nuclear reactions, thus a self-propagating series of these reactions is achieved and is called;
(a) Fission chain reaction
(b) Nuclear fusion
(c) Controlled nuclear reaction
(d) Uncontrolled nuclear reaction

Fission chain reaction

93. What is the process called when two light nuclei combine to form a heavy nucleus?
(a) Nuclear Fission
(b) Nuclear Fusion
(d) Electron Capture

Nuclear Fusion

94. In nuclear fusion, the loss in mass during the formation of a larger nucleus is manifested as:
(a) Heat
(b) Light
(c) Energy
(d) Sound

Energy

95. Where is a self-sustaining fusion reaction possible due to the required energy conditions?
(a) Laboratories
(b) Nuclear power plants
(c) Stars, including the Sun
(d) Earth’s atmosphere

Stars, including the Sun

96. What type of reaction is responsible for the energy production in stars like the Sun?
(a) Nuclear Fission
(b) Chemical Reaction
(c) Nuclear Fusion

Nuclear Fusion

97. Why is a self-sustaining fusion reaction challenging to achieve on Earth?
(a) Lack of suitable materials
(b) Insufficient technology
(c) High energy requirements
(d) Environmental concerns

High energy requirements

98. What is the result of the direct collision of protons in the proton-proton cycle?
(a) Formation of Deuterium
(b) Production of Helium Nuclei
(c) Release of Neutrons
(d) None of these

Formation of Deuterium

99. What happens when a deuteron combines with another proton in the proton-proton cycle?
(a) Formation of Tritium
(b) Production of Helium-3
(c) Release of neutrons
(d) Formation of Helium-2

Production of Helium-3

100. In the final stage of the proton-proton cycle, what is formed with the release of two protons?
(a) Helium-3
(b) Helium-4
(c) Beryllium-7
(d) Carbon-12

Helium-4

101. What is the term for the radiation that all living creatures have been exposed to from the beginning of time?

102. Which of the following is NOT a source of natural radiation?

103. The earth, and all living things on it, is constantly bombarded by radiations from space. What is this type of radiation called?

104. What causes variations in the dose of cosmic radiation in different parts of the world?
(a) Earth’s Magnetic Field
(b) Atmospheric Pressure
(c) Ocean Currents
(d) Lunar Phases

Earth’s Magnetic Field

(a) Only in the atmosphere
(b) In the soil, water, and vegetation
(c) Exclusively in mountainous regions
(d) Limited to urban areas

In the soil, water, and vegetation

106. What is the term for the radiation originating from isotopes like potassium-40, carbon-14, and lead 210 inside the human body?

107. Which isotopes contribute to internal radiation in the human body from birth?
(a) Uranium-235 and Thorium-232
(d) Tritium and Cesium-137

108. What is the general term for the acute effects of radiation, including symptoms like nausea, vomiting, fever, diarrhea, and loss of hair?