1. The spontaneous emission of radiation from unstable nuclei is called
A) Radioactivity
B) Fusion
C) Fission
D) Ionization
Answer: A) Radioactivity
Explanation: Radioactivity is the natural process where unstable atomic nuclei emit radiation to attain stability.
2. Radioactivity is a property of
A) Unstable atoms
B) Stable atoms
C) Electrons
D) Molecules
Answer: A) Unstable atoms
3. The scientist who discovered radioactivity was
A) Henri Becquerel
B) Marie Curie
C) Rutherford
D) Bohr
Answer: A) Henri Becquerel
Explanation: Becquerel discovered radioactivity while studying uranium salts in 1896.
4. The husband and wife team who studied radioactive substances were
A) Pierre and Marie Curie
B) Bohr and Einstein
C) Thomson and Rutherford
D) Newton and Faraday
Answer: A) Pierre and Marie Curie
5. The element discovered by the Curies is
A) Radium
B) Uranium
C) Thorium
D) Plutonium
Answer: A) Radium
6. The element from which radioactivity was first observed is
A) Uranium
B) Radium
C) Polonium
D) Thorium
Answer: A) Uranium
7. Radioactivity is a
A) Nuclear phenomenon
B) Chemical reaction
C) Mechanical process
D) Optical process
Answer: A) Nuclear phenomenon
8. The particles or rays emitted during radioactivity are called
A) Radiations
B) Electrons
C) Photons
D) Protons
Answer: A) Radiations
9. There are mainly how many types of radioactive emissions?
A) Three
B) Two
C) Four
D) Five
Answer: A) Three
Explanation: They are alpha (α), beta (β), and gamma (γ) radiations.
10. Alpha particles are
A) Helium nuclei
B) Electrons
C) Protons
D) Neutrons
Answer: A) Helium nuclei
11. Beta particles are
A) Electrons
B) Protons
C) Neutrons
D) Positrons
Answer: A) Electrons
12. Gamma rays are
A) Electromagnetic waves
B) Charged particles
C) Neutrons
D) Protons
Answer: A) Electromagnetic waves
13. Which of the following is neutral?
A) Gamma rays
B) Alpha rays
C) Beta rays
D) Positrons
Answer: A) Gamma rays
14. Which radiation has the greatest penetrating power?
A) Gamma rays
B) Beta rays
C) Alpha rays
D) All equal
Answer: A) Gamma rays
15. Which radiation is the most ionizing?
A) Alpha rays
B) Beta rays
C) Gamma rays
D) X-rays
Answer: A) Alpha rays
16. Alpha rays can be stopped by
A) A sheet of paper
B) A block of lead
C) Thick wall
D) Wood
Answer: A) A sheet of paper
17. Beta rays can be stopped by
A) Thin aluminum sheet
B) Paper
C) Glass sheet
D) Thick wood
Answer: A) Thin aluminum sheet
18. Gamma rays can be stopped by
A) Thick lead sheet
B) Paper
C) Wood
D) Plastic
Answer: A) Thick lead sheet
19. The radiation that carries positive charge is
A) Alpha particle
B) Beta particle
C) Gamma ray
D) Neutron
Answer: A) Alpha particle
20. The radiation that carries negative charge is
A) Beta particle
B) Alpha particle
C) Gamma ray
D) Proton
Answer: A) Beta particle
21. The emission of gamma rays does not change
A) Mass number or atomic number
B) Mass number only
C) Atomic number only
D) Energy of the atom
Answer: A) Mass number or atomic number
22. The speed of alpha particles is
A) Less than that of light
B) Equal to speed of light
C) More than light
D) Same as sound
Answer: A) Less than that of light
23. The speed of gamma rays is
A) Equal to the speed of light
B) Less than sound
C) Variable
D) Zero
Answer: A) Equal to the speed of light
24. Radioactive decay produces
A) Heat and radiation
B) Coldness
C) Sound
D) Electricity
Answer: A) Heat and radiation
25. Radioactivity was first observed in which compound?
A) Uranium salt
B) Lead nitrate
C) Iron oxide
D) Sodium chloride
Answer: A) Uranium salt
26. The unit of radioactivity is
A) Becquerel (Bq)
B) Joule
C) Ohm
D) Ampere
Answer: A) Becquerel
Explanation: 1 Bq = 1 disintegration per second.
27. The older unit of radioactivity is
A) Curie (Ci)
B) Joule
C) Weber
D) Tesla
Answer: A) Curie
28. The activity of a radioactive substance depends on
A) Number of undecayed atoms
B) Temperature
C) Pressure
D) Light
Answer: A) Number of undecayed atoms
29. The time taken for half of a radioactive material to decay is called
A) Half-life
B) Lifetime
C) Mean life
D) Duration
Answer: A) Half-life
30. The half-life of Carbon-14 is about
A) 5730 years
B) 500 years
C) 100 years
D) 10 years
Answer: A) 5730 years
31. The half-life of a radioactive substance depends on
A) Nature of the isotope
B) Temperature
C) Pressure
D) Amount of sample
Answer: A) Nature of the isotope
32. The half-life of a substance is independent of
A) Physical and chemical conditions
B) Mass
C) Volume
D) Temperature
Answer: A) Physical and chemical conditions
33. The disintegration of a radioactive atom is
A) Spontaneous and random
B) Regular
C) Predictable
D) Controlled
Answer: A) Spontaneous and random
34. Radioactive decay continues until
A) A stable nucleus is formed
B) The atom explodes
C) Energy is zero
D) Heat is lost
Answer: A) A stable nucleus is formed
35. The first artificial radioactive element was
A) Phosphorus-30
B) Uranium-235
C) Carbon-14
D) Radium-226
Answer: A) Phosphorus-30
36. Artificial radioactivity was discovered by
A) Irene Curie and Joliot Curie
B) Henri Becquerel
C) Rutherford
D) Bohr
Answer: A) Irene Curie and Joliot Curie
37. A device used to detect and measure radiation is
A) Geiger-Müller counter
B) Photometer
C) Microscope
D) Barometer
Answer: A) Geiger-Müller counter
38. The radioactive isotope used in cancer treatment is
A) Cobalt-60
B) Carbon-14
C) Sodium-24
D) Uranium-235
Answer: A) Cobalt-60
39. The radioactive isotope used in carbon dating is
A) Carbon-14
B) Uranium-238
C) Thorium-232
D) Iodine-131
Answer: A) Carbon-14
40. The isotope used in thyroid treatment is
A) Iodine-131
B) Cobalt-60
C) Phosphorus-32
D) Sodium-24
Answer: A) Iodine-131
41. The isotope used to study blood circulation in the body is
A) Sodium-24
B) Carbon-14
C) Cobalt-60
D) Iodine-131
Answer: A) Sodium-24
Explanation: Sodium-24 emits gamma radiation and is used as a tracer to observe blood flow and circulation.
42. The radioactive isotope used to study plant metabolism is
A) Phosphorus-32
B) Iodine-131
C) Carbon-14
D) Uranium-235
Answer: A) Phosphorus-32
Explanation: Phosphorus-32 helps trace phosphorus movement in plants for agricultural studies.
43. The isotope used to detect leaks in gas pipelines is
A) Argon-41
B) Carbon-14
C) Iodine-131
D) Sodium-24
Answer: A) Argon-41
Explanation: Argon-41 is a radioactive tracer gas used to detect leaks in closed systems.
44. The radiation used for sterilizing medical instruments is
A) Gamma rays
B) Alpha rays
C) Beta rays
D) Ultraviolet rays
Answer: A) Gamma rays
Explanation: Gamma rays kill bacteria and viruses and are used for sterilization in hospitals.
45. The radiation used to preserve food for long durations is
A) Gamma rays
B) X-rays
C) Beta rays
D) Ultraviolet rays
Answer: A) Gamma rays
Explanation: Gamma irradiation destroys microorganisms, keeping food fresh for longer periods.
46. The radioactive element found in luminous watch dials is
A) Radium
B) Uranium
C) Thorium
D) Cobalt
Answer: A) Radium
Explanation: Radium glows in the dark due to its continuous radiation.
47. Radioactive decay produces
A) Energy in the form of heat and radiation
B) Sound energy
C) Electric energy only
D) Light only
Answer: A) Energy in the form of heat and radiation
48. The energy released in radioactive decay comes from
A) The nucleus
B) The electrons
C) The atom as a whole
D) Chemical bonds
Answer: A) The nucleus
Explanation: Nuclear energy is released when the nucleus changes into a more stable form.
49. Radioactivity is independent of
A) Temperature, pressure, and chemical state
B) Number of atoms
C) Mass of sample
D) Energy absorbed
Answer: A) Temperature, pressure, and chemical state
50. The instrument used to detect radiation is
A) Geiger-Müller counter
B) Microscope
C) Barometer
D) Photometer
Answer: A) Geiger-Müller counter
51. The process by which one element changes into another due to radioactivity is called
A) Transmutation
B) Transformation
C) Translocation
D) Translation
Answer: A) Transmutation
Explanation: During radioactive decay, a nucleus changes to another element through emission of particles.
52. Artificial radioactivity was discovered by
A) Irene Curie and Frederic Joliot-Curie
B) Rutherford
C) Bohr
D) Einstein
Answer: A) Irene Curie and Frederic Joliot-Curie
53. The first artificially radioactive element produced was
A) Phosphorus-30
B) Uranium-235
C) Radium-226
D) Thorium-232
Answer: A) Phosphorus-30
54. Artificial radioactivity is caused by
A) Bombarding stable nuclei with particles
B) Heating the atom
C) Chemical reactions
D) Magnetic field
Answer: A) Bombarding stable nuclei with particles
55. Radioactive isotopes are used in medicine for
A) Diagnosis and treatment
B) Food preservation only
C) Decoration
D) Light production
Answer: A) Diagnosis and treatment
56. The isotope used to detect cancer is
A) Cobalt-60
B) Carbon-14
C) Sodium-24
D) Argon-41
Answer: A) Cobalt-60
Explanation: Cobalt-60 emits gamma rays used to destroy cancerous cells.
57. The device used to monitor radiation exposure in workers is
A) Dosimeter
B) Voltmeter
C) Barometer
D) Galvanometer
Answer: A) Dosimeter
58. The radioactive isotope used in smoke detectors is
A) Americium-241
B) Uranium-235
C) Radium-226
D) Carbon-14
Answer: A) Americium-241
Explanation: It emits alpha particles that help detect smoke in the air.
59. The isotope used in radiocarbon dating is
A) Carbon-14
B) Cobalt-60
C) Uranium-238
D) Sodium-24
Answer: A) Carbon-14
60. The process of determining the age of fossils using radioactivity is called
A) Radiocarbon dating
B) Radiotherapy
C) Radio tracing
D) Photometry
Answer: A) Radiocarbon dating
61. The isotope used in nuclear power generation is
A) Uranium-235
B) Carbon-12
C) Oxygen-16
D) Sodium-24
Answer: A) Uranium-235
62. Radioactive elements emit
A) Alpha, beta, and gamma rays
B) Light rays only
C) X-rays only
D) Sound waves
Answer: A) Alpha, beta, and gamma rays
63. The radioactive element used in luminous paints is
A) Radium
B) Iron
C) Sodium
D) Phosphorus
Answer: A) Radium
64. A half-life of a substance means
A) Time taken for half atoms to decay
B) Half energy released
C) Time for complete decay
D) None
Answer: A) Time taken for half atoms to decay
65. The decay rate of a radioactive substance decreases
A) Exponentially with time
B) Linearly
C) Constantly
D) Irregularly
Answer: A) Exponentially with time
66. The process of radioactive decay continues
A) Until a stable nucleus is formed
B) Indefinitely
C) Only at low temperature
D) Only at high pressure
Answer: A) Until a stable nucleus is formed
67. The radiation most dangerous to human tissue is
A) Gamma rays
B) Beta rays
C) Alpha rays
D) Infrared rays
Answer: A) Gamma rays
68. The unit of radiation dose absorbed by the body is
A) Gray (Gy)
B) Joule
C) Volt
D) Watt
Answer: A) Gray (Gy)
69. The unit that measures biological damage from radiation is
A) Sievert (Sv)
B) Curie
C) Joule
D) Ohm
Answer: A) Sievert (Sv)
70. Excessive exposure to radiation causes
A) Cancer and genetic defects
B) Increase in body strength
C) Muscle growth
D) Faster aging only
Answer: A) Cancer and genetic defects
71. The process of radioactive decay produces
A) New elements
B) Same element
C) Light only
D) Electric charge only
Answer: A) New elements
72. Nuclear reactors produce energy mainly by
A) Controlled fission
B) Fusion
C) Combustion
D) Ionization
Answer: A) Controlled fission
73. The process of converting a stable nucleus into a radioactive one is called
A) Artificial transmutation
B) Radioactive decay
C) Fusion
D) Ionization
Answer: A) Artificial transmutation
74. The particles emitted in radioactivity affect
A) Photographic plates
B) Magnetic field
C) Chemical reaction
D) Light color
Answer: A) Photographic plates
75. The radioactivity of an element is measured by
A) Geiger counter
B) Barometer
C) Thermometer
D) Electroscope
Answer: A) Geiger counter
76. The rate of radioactive decay depends on
A) Number of undecayed nuclei
B) Temperature
C) Light intensity
D) Pressure
Answer: A) Number of undecayed nuclei
77. The number of disintegrations per second of a sample is called
A) Activity
B) Half-life
C) Mass
D) Density
Answer: A) Activity
78. Radioactive decay series ends when
A) Stable lead isotope is formed
B) All atoms vanish
C) Energy stops
D) Uranium forms
Answer: A) Stable lead isotope is formed
79. The element used as fuel in nuclear reactors is
A) Uranium or Plutonium
B) Iron
C) Copper
D) Sodium
Answer: A) Uranium or Plutonium
80. The radiation used in medical imaging is
A) Gamma rays
B) Ultraviolet rays
C) Infrared rays
D) Microwaves
Answer: A) Gamma rays
81. The radiation that causes maximum ionization in air is
A) Alpha radiation
B) Beta radiation
C) Gamma radiation
D) X-rays
Answer: A) Alpha radiation
82. The isotope used in checking pipeline corrosion is
A) Sodium-24
B) Carbon-14
C) Uranium-235
D) Iodine-131
Answer: A) Sodium-24
83. The radiation most penetrating through human skin is
A) Gamma rays
B) Alpha rays
C) Beta rays
D) Visible light
Answer: A) Gamma rays
84. The process by which the nucleus loses energy without changing its structure is
A) Gamma emission
B) Alpha decay
C) Beta decay
D) Fission
Answer: A) Gamma emission
85. The scientist who explained nuclear structure was
A) Rutherford
B) Bohr
C) Curie
D) Becquerel
Answer: A) Rutherford
86. The isotope used for detecting water pollution is
A) Tritium
B) Iodine-131
C) Sodium-24
D) Phosphorus-32
Answer: A) Tritium
87. The radioactive element naturally found in soil is
A) Uranium
B) Iron
C) Silver
D) Copper
Answer: A) Uranium
88. Radioactive elements occur naturally in
A) Earth’s crust
B) Oceans
C) Atmosphere only
D) Plants
Answer: A) Earth’s crust
89. The instrument used to monitor radiation level in nuclear plants is
A) Geiger counter
B) Thermometer
C) Barometer
D) Manometer
Answer: A) Geiger counter
90. The isotope used in detecting tumors is
A) Cobalt-60
B) Sodium-24
C) Uranium-235
D) Iodine-131
Answer: A) Cobalt-60
91. The radioactive waste is disposed of by
A) Deep underground storage
B) Throwing in rivers
C) Burning in air
D) Sunlight exposure
Answer: A) Deep underground storage
92. The radiation that can cause genetic mutations is
A) Gamma rays
B) Alpha rays
C) Infrared rays
D) Microwaves
Answer: A) Gamma rays
93. The radiation used for industrial thickness testing is
A) Beta rays
B) Gamma rays
C) Alpha rays
D) Infrared rays
Answer: A) Beta rays
94. The radioactive element used in nuclear submarines is
A) Uranium
B) Sodium
C) Iron
D) Carbon
Answer: A) Uranium
95. The first person to coin the term “radioactivity” was
A) Marie Curie
B) Becquerel
C) Rutherford
D) Bohr
Answer: A) Marie Curie
96. The radiation that can be deflected by electric and magnetic fields is
A) Alpha and Beta rays
B) Gamma rays only
C) Neutrons only
D) None
Answer: A) Alpha and Beta rays
97. The isotope used in determining groundwater age is
A) Tritium
B) Sodium-24
C) Carbon-14
D) Cobalt-60
Answer: A) Tritium
98. Radioactivity is commonly measured by
A) Geiger counter and Scintillation counter
B) Voltmeter
C) Hydrometer
D) Spectrometer
Answer: A) Geiger counter and Scintillation counter
99. The energy released in radioactivity is called
A) Nuclear energy
B) Chemical energy
C) Thermal energy
D) Mechanical energy
Answer: A) Nuclear energy
100. The ultimate goal of radioactive decay is to form
A) A stable nucleus
B) A charged atom
C) A heavier nucleus
D) A moving atom
Answer: A) A stable nucleus