Unit 16: NUCLEAR PHYSICS

Test Chapter #16

1.Of the following, which has the smallest rest energy?
(A) A neutron (B) An ion
(C) An electron (D) A proton
2.The isotopes of an element:
(A) Cannot be separated at all
(B) Have similar chemical behavior
(C) Occur well separated in nature
(D) Cannot be separated by physical methods
3.Two protons are separated by 10-16 m. The nuclear (N), electrostatic (E), and gravitational (G)
forces between these protons, in order of increasing strength, are:
(A) E, N, G (B) G, E, N
(C) N, G, E (D) G, N, E
4.The binding energy of a nucleus is the energy that must be supplied to:
(A) Remove a nucleon (B) Remove a beta particle
(C) Remove an alpha particle
(D) Separate the nucleus into its constituent nucleons
5.If a nucleus has mass “M”, “Z” protons (mass mp), and “N” neutrons (mass mn), its binding energy
is equal to:
(A) Mc2 (B) (Zmp + Nmn – M)c2
(C) (M – Zmp – Nmn)c2 (D) (Nmp + Nmn)c2
6.Let “A” be the mass number and “Z” be the atomic number of a nucleus. Which of the following is
approximately correct for light nuclei?
(A) Z = 2A (B) Z = A/2
(C) Z = A (D) Z = √A
7.The relation between the disintegration constant “⅄” and the half life T of a radioactive substance
is:
(A) ⅄ = 2T (B) ⅄ = 2/T
(C) ⅄ = 1/T (D) ⅄T = ln2
8.Possible units for the disintegration constant “⅄” are:
(A) kg/s (B) Hour
(C) s/kg (D) Day-1
9.The half life of radium is about 1600 years. If a rock initially contains 1 g of radium, the amount
left after 6400 years will be about:
(A) 938 mg (B) 31 mg
(C) 62 mg (D) 16 mg
10. Starting with a sample pure “Cu, 7/8 of it decays into Zn in 15 minutes. The crossponding half-
life is:
(A) 15 minutes (B) 7 minutes
(C) 5 minutes (D) 3.75 minutes
11. Radioactive Sr has a half life of 30 years. What percent of a sample of 90Sr will remain after 60
90

years?
(A) 0% (B) 50%
(C) 25% (D) 75%
12. The half-life of a radioactive isotope is 6.5 h. if there are initially 48 x 1032 atoms of this isotope,
the number of atoms of this isotope remaining after 26 h is:
 (A) 12 x 1032 (B) 3 x 1032
32
(C) 6 x 10 (D) 6 x 104
13. An alpha particle is:
(A) A helium atom with two electrons removed
(B) An aggregate of two or more electrons
(C) A hydrogen atom
(D) The ultimate unit of positive charge
14. Radioactive polonium, 214Po (Z = 84), decays by alpha emission to:
(A) 214Po (Z = 84) (B) 214At (Z = 85)
(C) 210Pb (Z = 82) (D) 218Po (Z = 84)
15. A beta particle is:
(A) A helium nucleus (B) A radioactive element
(C) An electron or a positron (D) Any negative particle
16. A radioactive atom “X” emits a β – particles. The resulting atom:
(A) Must be very reactive chemically
(B) Has an atomic number that is one more than that of “X”
(C) Has a mass number that is one less than that of “X”
(D) Must be radioactive
17. A nucleus with mass number “A” and atomic number “Z” undergoes β+ decay. The mass
number and atomic number, respectively, of the daughter nucleus are:
(A) A – 1, Z – 1 (B) A + 1, Z – 1
(C) A, Z – 1 (D) A, Z + 1
18. An atom of 235U (Z = 92) disintegrates to 207Pb (Z = 82) with a half-life of about a billion years by
emitting seven alpha particles and β-particles:
(A) 3 (B) 5
(C) 4 (D) 6
-
19. A certain nucleus, after absorbing a neutron, emits a β and then splits into two alpha particles.
The (A, Z) of the original nucleus must have been:
(A) 6, 2 (B) 7, 2
(C) 6, 3 (D) 7, 3
20. Most of energy produced by the sun is due to:
(A) Nuclear fission (B) Chemical reaction
(C) Nuclear fusion (D) Gravitational collapse
21. The first step of the proton – proton cycle is:
(A) 1H + 1H → 2H (B) 1H + 1H → 2H + e-
1 1 2 +
(C) H + H → H + e (D) 1H + 1H → 2H + γ
22. Tick the correct statement:
(A) Moderate slow down the neutron
(B) Moderator absorber the neutron
(C) Moderator bring the neutrons of rest
(D) Moderator reflect the neutrons
23. Fission chain reaction in a nuclear reactor can be controlled by introducing:
(A) Iron rod (B) Cadmium rods
(C) Graphite rods (D) Platinum rods
24. Nuclei having the same mass number but different atomic number are:
(A) Isotopes (B) Isotones
(C) Isobars (D) Isomers
25. An α-particle is emitted from 88Ra226, what is the mass and atomic number of the daughter
nucleus?

Mass number Atomic number

A 224 84
B 220 80
C 222 86
D 226 87
26. Radioactive materials can be identified by measuring their:
(A) Hardness (B) Masses
(C) Densities (D) Half lives
235
27. The breakage of 92U produces the fragments as:
(A) Kr and Ba (B) Xe and Sr
(C) Sn and Mo (D) All of them
28. Plutonium can be fissioned by:
(A) Slow neutron (B) Very slow neutron
(C) Fast neutron (D) All of these
29. A pair of quark and anti-quark makes a:
(A) Meson (B) Photon
(C) Baryon (D) Proton
30. The rate of decay of a radioactive substance:
(A) Remains constant with time (B) Decrease with time
(C) Increase with time
(D) May increase or decrease with time
31. In nucleus fission reaction, when the products are 140Xe and 94Sr, the number of neutrons
emitted is:
(A) 4 (B) 2
(C) 3 (D) 1
32. When a radioactive nucleus emits a β – particle, the proton – neutron ratio:
(A) Remains the same (B) Decreases
(C) Increases (D) Equal to 1
33. Which one of the following isotopes of natural uranium undergoes a fission reaction with slow
neutrons?
(A) 23592U (B) 23892U
234
(C) 92U (D) 23692U
34. The amount of energy equivalent to “1u” is:
(A) 9.315 MeV (B) 931 MeV
(C) 93.45 MeV (D) 1.025 MeV
35. Energy given out per nucleon is p-p reaction is:
(A) 5.2 MeV (B) 6.4 MeV
(C) 6 MeV (D) 7.7 MeV
36. A sample contains “N” radioactive nuclei. After 4 half lives numbers of nuclei decayed is:
(A) N/16 (B) N/8
(C) 15N/16 (D) 7N/8
37. When α-particle is emitted from any nucleus, its mass number __________ and charge number
___________.
(A) Increases by 2, increases by 2
(B) Decreases by 4, decreases by 2
(C) Decreases by 4, increases by 2
(D) Decreases by 4, decreases by 4
38. The half of radioactive element depends on:
(A) Temperature (B) Nature of element
(C) Pressure
(D) Amount of radioactive substance
39. Types of quarks are:
(A) 4 (B) 8
(C) 6 (D) 10
40. Three up quarks combine to from a new particle, the charge on this particle is:
(A) +e (B) +3e
(C) +2e (D) +4e
41. The energy related per nucleon is greater in:
(A) Fission reaction (B) Chemical reaction
(C) Fusion reaction (D) All of these
42. γ – rays are absorbed by a sheet of:
(A) 1 5 mm of lead (B) 5 10
mm of lead
(C) 1 10 cm of lead (D) 10 100
mm of lead
43. γ – rays consist of:
(A) Helium nuclei (B) Radiations similar to x-rays
(C) Hydrogen nuclei (D) Neutrons
44. Half-life of radium – 226 is:
(A) 1820 years (B) 1620 years
(C) 1940 years (D) 1680 years
45. In nuclear reactors uranium is enriched up to:
(A) 1% to 2% (B) 2% to 3%
(C) 1% to 3% (D) 2% to 4%
46. Both Xenon and Cesium each have isotopes:
(A) 12 (B) 36
(C) 33 (D) 39
47. In unified mass scale, 1 u equals:
(A) 1.66 x 10-27 g (B) 1.66 x 10-24 g
(C) 12 g (D) 1.66 x 10-24 kg
48. Which of the following does not belong to “hadrons” group?
(A) Proton (B) Mesons
(C) Electrons (D) Neutrons
49. The energy released by fusion reaction of two deuterons into a helium nucleus is about:
(A) 24 MeV (B) 1.02 MeV
(C) 200 MeV (D) 7.7 MeV
50. Which one belongs to Lepton group?
(A) Electron (B) Neutrinos
 (C) Muons (D) All of these
51. A proton consists of quarks which are?
(A) Two up, one down (B) All up
(C) One up, two down (D) All down
52. Hydrogen bomb is an example:
(A) Nuclear fission (B) Chemical reaction
(C) Nuclear fusion (D) Chan reaction
53. Iron has atomic number 26. Naturally mined iron contains isotopes of mass numbers 54, 56, 57,
and 58. Which of the following statements is FALSE?
(A) Every atom of iron has 36 protons
(B) Some iron atoms have 30 neutrons
(C) Some iron atoms have 54 neutrons
(D) The isotopes may be separated in a mass spectrometer
54. The function of the control rods in a nuclear reactor is to:
(A) Increase fission by slowing down the neutrons
(B) Decrease the energy of the neutrons without absorbing them
(C) Increase the ability of the neutrons to cause fission
(D) Decrease fission by absorbing neutrons
55. The half life of a radioactive substance is:
(A) Half the time it takes for the entire substance to decay
(B) Usually about 50 years
(C) The time for radium to change into lead
(D) The time for half the substance to decay
56. A large collection of nuclei are undergoing alpha decay. The rate of decay at any instant is
proportional to:
(A) The number of un-decayed nuclei present at that instant
(B) The time since the decays started
(C) The time remaining before all have decayed
(D) The half-life of the decay
57. The half life of a radioactive isotope is 140 days. In how many days does the decay rate of a
sample of this isotope decrease to one-fourth of its initial decay rate?
(A) 35 (B) 280
(C) 105 (D) 210
58. The particle which has its mass number and charge number equal to zero:
(A) Proton (B) Neutron
(C) Electron (D) Photon
59. In an alpha decay the disintegration energy appears chiefly as:
(A) Photon energies
(B) The kinetic energies of the alpha and the daughter nucleus
(C) The excitation energy of the daughter nucleus
(D) The excitation energy of the alpha particle
60. The nuclei 6C13 and 7N14 can be described as:
(A) Isotones (B) Isobars
(C) Isotopes (D) Isomers
61. There are three lumps of a given radioactive substance. Their activity is in the ratio of 1:2:3
now. What will be the ratio of their activities at any further date?
(A) 1:2:3 (B) 3:2:1
 (C) 2:1:3 (D) 2:3:1
62. In the reaction represented by:
A A-4
ZX → Z-2Y → Z-2YA-4 → Z-1KA-4
The decay in the sequence is:
(A) α, β, γ (B) γ, α, β
(C) β, α, γ (D) α, γ, β
63. A nuclear reaction obeys:
(A) Law of conservation of mass
(B) Law of conservation of energy
(C) Law of conservation of charge
(D) All of these
64. The ratio of half-life times of two elements “A” and “B” is “TA/TB”. The ratio of respective
decay constant “⅄A/⅄B” is:
(A) TB/TA (B) (TA + TB)/TA
(C) TA/TB (D) None of these
65. In nucleus of uranium the number of neutrons will be:
(A) 92 (B) 143
(C) 235
(D) Different for different isotopes
66. During fusion of hydrogen into helium:
(A) Energy is absorbed (B) Energy is released
(C) Mass is increased due to energy absorption
(D) Mass is reduced due to energy absorption
67. The α-particle ionizes the particles in its way and adopt the path which is?
(A) Curved (B) Zig-Zag
(C) Straight (D) Straggling
68. The half of uranium – 238 is:
(A) 1.67 x 108 years (B) 4.5 x 108 years
(C) 3.3 x 109 years (D) 4.5 x 109 years
69. For chain reaction to buildup, the size of the radioactive target should be:
(A) 90 kg (B) Less than the critical size
(C) Greater than critical size (D) Equal to critical size
70. Which one of the following is NOT needed in a nuclear fission reactor?
(A) Moderator (B) Coolant
(C) Fuel (D) Accelerator
71. Half life of Radium is 1590 years. In how many years shall the earth loss all his radium due to
radioactive decay?
(A) 1590 x 106 years (B) 1590 x 1025 years
(C) 1590 x 1012 years (D) Never
72. Which one of the following radiation possesses maximum penetrating power?
(A) α-rays (B) γ-rays
(C) β-rays
(D) All have equal penetrating power
73. Radioactivity is a:
(A) Spontaneous activity (B) Self disintegration property
(C) Chemical property (D) Both A and B
74. Energy liberated when one atom of U-235 undergoes fission reaction is:
 (A) 200 MeV (B) 30 MeV
(C) 40 MeV (D) 20 MeV
75. Nuclear force exists between:
(A) Proton-proton (B) Neutron-Neutron
(C) Proton-Neutron (D) All of the above
76. Mass defect per nucleons is:
(A) Binding energy of nucleus (B) Average energy of nucleus
(C) Packing fraction
(D) All of above are one & same thing
77. Heavy radioactive elements eventually turn into:
(A) Barium (B) Hydrogen
(C) Lead (D) Radium
78. β-particle ionizes an atom:
(A) Through direct collision
(B) Through electrostatic repulsion
(C) Through electrostatic attraction (D) All of the above
79. Marie Curie and Pierre Curie discovered two new radioactive elements which?
(A) Uranium and Polonium (B) Radium and Uranium
(C) Polonium and Radium (D) Uranium and Plutonium
80. Radioactive decay obeys which one of the following data?
(A) N = Noe-⅄t (B) N = Noe-xt/2
(C) N = Noext (D) No = N(Iext)
81. Average energy required to remove one nucleon from the nucleus is called:
(A) Binding energy per nucleon (B) Destruction energy
(C) Energy of decay (D) All of above
82. Which one of the following possesses maximum velocity?
(A) α-rays (B) γ-rays
(C) β-rays
(D) All of the above have same speed
83. A particle having the mass of an electron and the charge of a proton is called:
(A) Antiproton (B) Gamma rays
(C) Positron (D) Photon
84. Which one of the following possesses greater penetrating power?
(A) α-rays (B) β-rays
(C) X-rays (D) Neutron
85. Which one of the following will be better shield against γ-rays?
(A) Ordinary water (B) Lead
(C) Heavy water (D) Aluminum
86. Sum of the mases of constituent nucleons as compared to the mass of the resultant nucleus is:
(A) Smaller (B) Same
(C) Greater
(D) Sometimes smaller some times greater
87. An α-particle is emitted from 88Ra226, what is the mass and atomic number of the daughter
nucleus?

Mass number Atomic number

A 224 84
 B 220 80
C 222 86
88. Strong nuclear force:
(A) Increase with magnitude of increasing charge
(B) Decreases with magnitude of increasing charger
(C) Is independent of charge
(D) Responsible of breakage of nuclei
89. During fission process, a large amount of:
(A) Heat energy is released (B) Chemical energy is released
(C) Nuclear energy if released (D) Light energy is released
90. Complete the reaction:
A A O
Z X → Z +1Y + −1 β + …+Q
(A) Neutrino (B) α-particle
(C) Anti-neutrino (D) Positron
91. If one or more of the neutrons emitted during fission can be used to build up further fission
then the reaction is self-sustained and is known as:
(A) Fission chain reaction (B) Chain reaction
(C) Fusion reaction (D) Chemical reaction
92. Separation of the isotopes of uranium requires a physical, rather than chemical, method
because:
(A) Maxing other chemicals with uranium is too dangerous
(B) The isotopes are chemically the same
(C) The isotopes have exactly the same number of neutrons per nucleus
(D) Natural uranium contains only 0.7% 235U
93. The path of β-particle is:
(A) Rectilinear (B) Zigzag or erratic
(C) Carved (D) Elliptical
94. β-particles possess greater penetration power than that of α-particle due to its:
(A) Smaller ionization power (B) Same ionization power
(C) Energy is not conserved
(D) Neither greater nor smaller ionization power
95. average distance covered by α-particle in air before its ionizing power ceases is called its:
(A) Trajectory (B) Firing level
(C) Range (D) Limit
96. A α-particle can produce fluorescence in:
(A) Zns (B) Sodium iodide
(C) Barium Palatino cyanide (D) All of the above
97. The penetration power of β-particle as compared to α-particle is:
(A) 10 times more (B) 100 times less
(C) 100 times more (D) 10 times less
98. The fuel/ fuels used in the reactor are nowadays:
(A) Plutonium - 239 (B) Uranium – 235
(C) Uranium – 233 (D) All of these
99. For atomic nuclei, the binding energy per nucleon:
(A) Increases continuously with increase in mass number
(B) Decreases continuously with increase in mass number
 (C) Remains constant with increase in mass number
(D) First increases and then decreases with increase in mass number
100. Subatomic particles are divided into:
(A) Photons (B) Hadrons
(C) Leptons (D) All of these
101. The charges on the quarks are:
(A) One unit (B) Fraction
(C) +2e (D) +e
102. Enriched uranium is better as a fuel for a nuclear reactor because it has greater proportion of:
(A) 233U (B) 238U
235
(C) U (D) 239U
103. If a radioactive isotope of silver has a half-life of about 7.5 days after 15 days the remaining
isotope of its original is:
(A) 25% (B) 7.5%
(C) 50% (D) 15%
104. A nuclide 22086R decays to a new nuclide by two α-emissions, the nuclide S is:
(A) 21284S (B) 22080S
212
(C) 82S (D) 21082S
105. Which of the following are elementary particles?
(A) Photons (B) Neutrons
(C) Protons (D) Mesons
106. Fluorescence is the property of:
(A) High frequency particles
(B) Moderate frequency particles
(C) Low frequency particles
(D) Visible light
107. An explosion does not result from a small piece of 235U because:
(A) It does not fission
(B) The neutrons released move too fast
(C) 218U is required
(D) To many neutrons escape, preventing a chain reaction from starting
108. In the uranium disintegration series:
(A) The emission of a β- particle increases the mass number “A” by one and decreases the atomic
number “Z” by one.
(B) The disintegrating element merely ejects atomic electrons
(C) The emission of an α particle decreases the mass number “A” by four and decreases the atomic
number “Z” by two
(D) The nucleus always remains unaffected
109. Energy given out per nucleon in p – p reaction is:
(A) 5.2 MeV (B) 6 MeV
(C) 6 MeV (D) 6.4 MeV
110. In a nuclear reaction a beam of α – particle strike a target of 60Ni. The product of this reaction
might be:
(A) 63Zn + n (B) 61Ni + n
63
(C) Cu + n (D) All of these
111. By emitting β-particle and γ-particle simultaneously the nucleus changes its charge by:
(A) Losses by 1 (B) No change will observed
 (C) Increases by 1 (D) Increase by 2
112. The binding energy per nucleon:
(A) Increases for all fission events
(B) Decreases for all fission events
(C) Increases for some, but not all, fission events
(D) Decreases for some, but not all, fission events
113. The amount of energy required to break the nucleus is called its:
(A) Nuclear energy (B) Potential energy
(C) Kinetic energy (D) Binding energy
114. Among the following select the correct statement:
(A) The rate of disintegration is directly proportional to the number of atoms present in the sample at
that instant
(B) Equal fractions disintegrate in equal intervals of time
(C) Radioactive sample takes an infinite time to disintegrate
(D) All of the above
115. Beta particles from various radioactive sources all have:
(A) The same mass (B) The same charge
(C) The same speed (D) The same deflection
116. After two half-lives, the numbers of un -decayed nuclei of an element are:
(A) N (B) N/4
(C) N/2 (D) 3N/4
117. γ-rays are emitted by the de-excitation of:
(A) An atom (B) An element
(C) Molecule (D) Nucleus
118. Radioactive 90Sr has a half-life of 30 years. What percent of sample of 90Sr will remain after 60
years?
(A) 0% (B) 50%
(C) 25% (D) 75%
119. At the end of 14 min, 1/16 of a sample of radioactive polonium remains. The corresponding
half-life is:
(A) (7/8) min (B) (7/4) min
(C) (8/7) min (D) (7/2) min
120. Half-life of iodine – 131 is 8 days and it weight 20 mg. after 4 half-lives, the amount left un-
decayed will be:
(A) 2.5 mg (B) 0.625 mg
(C) 1.25 mg (D) 0.3125 mg
121. An α-particle contains:
(A) “1” proton and “1” neutron
(B) “3” protons and “3” neutrons
(C) “2” protons and “2” neutrons
(D) “4” protons and “4” neutrons
122. Nuclear fission experiments show that the neutrons split the uranium nuclei into two fragments
of about the same size. This process is accompanied by the emission of several:
(A) Protons and positrons (B) Neutrons
(C) α-particles (D) Protons and α-particles
210
123. Bi (an isotope of bismuth) has a half life of 5.0 days. The time for three quarters of a sample
of 210Bi to decay is:
 (A) 2.5 days (B) 15 days
(C) 10 days (D) 20 days
124. Binding energy for deuteron nucleus is given by:
(A) 2.8 MeV (B) 2.28 MeV
(C) 2.23 MeV (D) 2.25 MeV
125. Which is the equation of beta decay?
A A O A A O
(A) Z X → Z +1Y + +1e (B) X → Z +1Y + −1e
Z
A A −1 O A A −1 O
(C) Z X → Z Y + −1e (D) X → Z −1Y + −1e
Z
126. The particles equal in mass or greater than protons are called:
(A) Mesons (B) Muons
(C) Baryons (D) Electrons
127. Starting with a sample of “Cu, 7/8 of it decays into “Zn” in 15 minutes. The corresponding half-
life is:
(A) 15 minutes (B) 7 minutes
(C) 5 minutes (D) 3.75 minutes
128. Which is true for both α-particles and γ-rays?
(A) They cause ionization in air
(B) They can be deflected by magnetic field
(C) They can be deflected by electric field
(D) They can penetrate a few millimeters of aluminum
129. A neutron decays within the nucleus producing:
(A) One P, one v and β+ (B) One β+, one β- and v
(C) One P, one β and one v
-
(D) All of the above
130. When a radioactive nuclide decays consecutively by emitting an α-particle, a β-particle and γ-
rays the change in nucleon number and atomic number are:

A B C D

Change in mass -2 -3 -3 -4
number
Change in atomic -3 -2 -3 -1
number
131. When a nucleus with atomic number “Z” and mass number “A” undergoes a radioactive decay
process:
(A) Both “Z” and “A” will decrease, if the process is α-decay
(B) “Z” will decrease but “A” will not change, if the process is β + decay
(C) “Z” will increase but “A” will not change, if the process is β - decay
(D) All of these
132. The half-life of a radioactive element is such that 7/8 of a quantity of it decays in 12 days what
fraction of it reman un-decayed after 24 day?
(A) 0 (B) 1/128
(C) 1/64 (D) 1/32
133. Decay constant “⅄” given by:
−∆ N / N
(A) (B) -N∆N∆t
∆T
∆ N/N −∆ T
(C) (D)
∆T ∆ N/N
134. The radioactive nuclide 22888Ra decays by emission of three α-particles. The nuclide “X” finally
formed is:
(A) 22084X (B) 22286X
216
(C) 82X (D) 21588X
135. The ionizing power when we compare α,β and γ rays is:
(A) Same in all the three (B) Maximum in α-particles
(C) Maximum in β-particles (D) Maximum in γ-rays
136. The mass of α-particles is:
(A) 4Mp (B) 4Ma
(C) 2Mp + 2Mn (D) 2Mc + 2Mp
137. Which one of the following combinations of radioactive decay results in the formation of an
isotope of original nuclide?
(A) α and β (B) α and two β
(C) Two α and β (D) α and four β
138. Which one of the following is formed during beat emission?
(A) Isobars (B) Isotones
(C) Isotopes (D) Isomers
139. A certain radioactive nuclide of mass number “X” decays by beta emission and γ emission to a
second nuclide of mass number “Y”, the correct relation between “X” and “Y” is:
(A) Y = X – 4 (B) Y = X – 1
(C) Y = X + 1 (D) Y = X
140. The half-life of radium is about 1600 years. If 100g radium existing now, 25g will remain
undecayed after:
(A) 4800 years (B) 6400 years
(C) 6400 years (D) 3200 years
141. Which nucleus is most stable nucleus?
(A) 3115P (B) 5626Fe
141
(C) 56Ba (D) 22688Ra
142. In γ-emission atomic number of nucleus:
(A) Increases by 1 (B) Decreases by 1
(C) Increases by 2 (D) No change
143. In radioactivity, the rate of decay:
(A) Can be increased by magnetic field
(B) Can be decreased by the magnetic fields
(C) Can be kept constant by the electric field
(D) In not effected by electric and magnetic field
144. The graph shows the activity R as a function of time “t” for three radioactive samples. Rank the
samples according to their half-lives, shorter to longest.

(A) 1, 2, 3 (B) 2, 1, 3
(C) 1, 3, 2 (D) 2, 3, 1
145. Sequence of radiation emitted in the radioactive process:
 A A A−4 A−4
Z X → Z +1Y + Z−1L → Z−1L
(A) α, β, γ (B) γ, β, α
(C) β, γ, α (D) β, α, γ
222 210
146. 86A → 84B in this reaction how many “α” and “β” emission have occurred:
(A) 6α, 3β (B) 6α, 4β
(C) 4α, 3β (D) 3α, 4β
147. If 10% of a radioactive substance decays in every 5 years, then the percentage of the substance
what will decayed in 20 years will be:
(A) 40% (B) 50%
(C) 65.6% (D) 34.4%
148. If “A” is the atomic mass and “Z” is the atomic number of an atom, then the charge on its
nucleus will be:
(A) + (A – Z)e (B) + (Z)e
(C) + (Z – A)e (D) + (A)e
149. An alpha particle travels a well-defined distance before coming to rest. This distance is known
as range of the particle. This range depends upon.
(A) Charge of the particle (B) Mass of the particle
(C) Energy of the particle (D) All of these
150. Which of following is a correct statement?
(A) Protons and neutrons have exactly same mass
(B) Gamma rays are higher energy neutrons
(C) Alpha particle are single ionized helium neutrons
(D) Beta rays are same as cathode rays
151. Ar – 40, Ca – 40 and K – 40 are:
(A) Isotopes of each other (B) Isotones of each other
(C) Isobars of each other (D) All of these
152. If 15/16 of radioactive atoms decay in 16 hours, the half-life of element is:
(A) 16 hours (B) 8 hours
(C) 4 hours (D) 2 hours
153. Which one of following process is not related to radioactive disintegration?
(A) Positron emission (B) Beta decay
(C) Alpha decay (D) Nuclear fusion
154. If a nucleus AZX emits an alpha particle and resultant nuclear emits a beta particle, then atomic
charge and mass number of final nucleus will be:
(A) Z – 2, A – 4 (B) Z – 1, A – 4
(C) Z – 32, A – 4 (D) Z, A – Z
155. A nuclide 220R84 decay to a new nuclide S by two alpha emissions and two Beta emissions, the
nuclide S is:
(A) 218S84 (B) 216S84
212
(C) S82 (D) 216S82
156. The particles lighter than protons are called:
(A) Mesons (B) Muons
(C) Hadrons (D) Baryons
157. Radiation from a point source obeys the inverse square law. If the count rate at a distance of
1.0m from counter is 360 counts per minute. The count rate at the distance of 3m will be:
(A) 90 count per minute (B) 40 count per minute
(C) 120 count per minute (D) 45 count per minute
158. As mass number “A” varies which of quantity related to nucleus does not change?
(A) Mass (B) Volume
(C) Binding energy (D) Density
159. Particle not emitted by a radioactive substance are:
(A) γ-rays (B) Electrons
(C) Protons (D) 42He
160. Radioactivity is the phenomenon associated with:
(A) Production of radio waves
(B) Transmissions of radio waves
(C) Reception of radio waves
(D) Decay of atomic nucleus
161. Mass defect for Protium is:
(A) Very small (B) Very large
(C) Medium (D) Zero
-15
162. Two nucleons are at a separation of 1 x 10 m. the net nuclear force between them is F1 if both
are neutrons, F2 if both are protons, and F3 if one is a proton the other is neutrons then which of
the following is correct?
(A) F1 = F3 > F2 (B) F1 = F2 > F3
(C) F1 = F2 = F3 (D) F2 > F1 > F3
163. When a tritium captures a proton, it becomes:
(A) Neutron (B) Meson
(C) Alpha particle (D) Deuteron
164. α, β and γ-rays emitted by a radioactive substance are passed through a region containing a
magnetic field at right angles to their path. The energy gained will be:
(A) Maximum for α-rays (B) Maximum for β-rays
(C) Maximum for γ-rays (D) Zero for all of them
165. half-life of a radioactive element can be increased by:
(A) Increasing temperature (B) Changing volume
(C) Maximum for γ rays (D) Can’t be increased
166. A nucleons “Q” has notation YXQ which of following is an isotope of Q:
Y −1 Y
(A) XQ (B) X −1Q
Y Y −1
(C) X +1Q (D) X +1Q
232 208
167. The end product of the decay of 90Th is 82Pb. The number of alpha and beta particles
emitted are respectively:
(A) 3, 3 (B) 6, 4
(C) 6, 0 (D) 4, 6
168. A radioactive nucleus “X” undergoes a series of decays according to scheme:
α β α γ
X X1 X2 X3 X 4
→ → → →
If mass number and atomic number of “X” are 180 and 72 respectively. The corresponding
numbers for “X4” are:
(A) 176, 69 (B) 172, 69
(C) 176, 71 (D) 172, 71
169. The ratio of number of protons and the number of neutrons is:
(A) Almost one, in light elements
(B) Smaller than one, in heavy elements
 (C) Greater than one in heavy elements (D) Both A and B
170. When a β-particle is slowed down by the electric field of a charged particles in a sloid material,
the energy is radiated as:
(A) α-particles (B) β-particles
(C) X-rays (D) Both A and B
171. Due to the emission of beta particles by a thorium nucleus, we get:
(A) Radium (B) Protactinium
(C) Uranium (D) Radon
172. The weight of a radioactive element is 1g. after 3 days it becomes 0.25g. The half life of the
element is:
(A) 72 hours (B) 144 hours
(C) 36 Hours (D) Impossible fact
173. Outside a nucleus:
(A) Neutron is stable
(B) Proton and neutron both are stable
(C) Neutron is unstable
(D) Neither neutron nor proton is stable
174. The reciprocal of the decay constant is:
(A) Mean life (B) Frequency
(C) Half-life (D) Radioactivity constant