# 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

### Radioactivity

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
Show Answer

Nuclear Physics

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

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
Show Answer

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
Show Answer

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
Show Answer

Isotopes

To Download Complete Notes of Physics Notes 10 Class, Click on the given link.

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}}

Show Answer

\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
Show Answer

Protons and neutrons

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

Proton

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

Nucleons

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

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
Show Answer

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
Show Answer

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
Show Answer

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}

Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

20

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

Radioactivity

19. Which type of radiation involves the emission of He-4 nuclei?
(a) Alpha (\alpha) radiation
(b) Beta (\beta) radiation
(c) Gamma (\gamma) radiation
(d) None of these
Show Answer

Alpha (\alpha) radiation

20. An element with unstable nuclei undergoing spontaneous decay is said to be:
(a) Radiogenic element
(b) Stable element
(c) Decay element
(d) Radioactive element
Show Answer

Radioactive 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
Show Answer

Alpha, beta, gamma

22. Which type of radiation consists of high-energy electromagnetic radiations?
(a) Alpha (\alpha) radiation
(b) Beta (\beta) radiation
(c) Gamma (\gamma) radiation
(d) None of these
Show Answer

Gamma (\gamma) radiation

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

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

Alpha (\alpha) rays

29. Radioactivity occurs:
(a) With a defined pattern
(b) Randomly
(c) Predictably
(d) Controllably
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

High neutron-to-proton ratio

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

Electromagnetic radiation

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
Show Answer

High energy in the nucleus

36. What is the composition of gamma (\gamma) radiation?
(a) Electrons
(b) 2 protons and 2 neutrons
(c) High energy electromagnetic radiations
(d) Protons only
Show Answer

High energy electromagnetic radiations

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

+2

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

-1

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

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
Show Answer

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
Show Answer

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
Show Answer

Energy loss

43. What is ionization in term of radiation?
(a) Radiation absorption
(b) Splitting matter into positive and negative ions
(c) Penetration into materials
(d) Radioactive decay
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

Alpha (\alpha) particles

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

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
Show Answer

Nuclear transmutation

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

Parent

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

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
Show Answer

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
Show Answer

Reduced by two

54. Find the daughter nucleus when Radium-224 undergoes alpha decay.
(a) Radon-220
(b) Polonium-210
(c) Radium-226
(d) Thorium-230
Show Answer

Radon-220

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

3.70 \times 10^{10}

62. What are the names of the two radioactive elements discovered by the Curies?
(a) Uranium and Thorium
(b) Polonium and Radium
(c) Radon and Francium
(d) Neptunium and Plutonium
Show Answer

Polonium and Radium

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

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
Show Answer

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
Show Answer

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
Show Answer

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 \%
Show Answer

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}
Show Answer

1/16

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

Radioactive 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
Show Answer

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
Show Answer

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 \%
Show Answer

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
Show Answer

5,700 years

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

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
Show Answer

Between 2 and 6

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

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
Show Answer

20.334 minutes

78. What distinguishes Carbon-14 from other radioisotopes of carbon?
(a) Longer half-life
(b) Shorter half-life
(c) No radioactivity
(d) Higher atomic number
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
(b) To minimize radiation exposure
(c) To enhance therapeutic effects
(d) To increase gamma ray emission
Show Answer

To minimize radiation exposure

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
(c) Radioactive Decay
(d) Electron Capture
Show Answer

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
Show Answer

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
Show Answer

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
(d) Radioactive Decay
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

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
Show Answer

Helium-4

101. What is the term for the radiation that all living creatures have been exposed to from the beginning of time?
(a) Artificial Radiation
(b) Synthetic Radiation
(c) Natural Radiation
(d) Industrial Radiation
Show Answer

Natural Radiation

102. Which of the following is NOT a source of natural radiation?
(a) Cosmic Radiation
(b) Terrestrial Radiation
(c) Artificial Radiation
(d) Internal Radiation
Show Answer

Artificial Radiation

103. The earth, and all living things on it, is constantly bombarded by radiations from space. What is this type of radiation called?
(a) Terrestrial Radiation
(b) Cosmic Radiation
(c) Internal Radiation
(d) Industrial Radiation
Show Answer

Cosmic Radiation

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
Show Answer

Earth’s Magnetic Field

105. Where is radioactive material found in terrestrial radiation?
(a) Only in the atmosphere
(b) In the soil, water, and vegetation
(c) Exclusively in mountainous regions
(d) Limited to urban areas
Show Answer

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?
(a) Terrestrial Radiation
(b) Internal Radiation
(c) Cosmic Radiation
(d) Industrial Radiation
Show Answer

Internal Radiation

107. Which isotopes contribute to internal radiation in the human body from birth?
(a) Uranium-235 and Thorium-232
(b) Potassium-40, Carbon-14, and Lead-210
(c) Radon-222 and Polonium-210
(d) Tritium and Cesium-137
Show Answer

Potassium-40, Carbon-14, and Lead-210

108. What is the general term for the acute effects of radiation, including symptoms like nausea, vomiting, fever, diarrhea, and loss of hair?
(a) Chronic Radiation
(b) Radiation Fatigue
(c) Radiation Sickness
(d) Radiation Exposure
Show Answer

Radiation Sickness