Free Nuclear Physics MCQs with Answers
1,254 Nuclear Physics MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Atomic nuclei contain protons and neutrons, with nuclear size, mass defect and binding energy describing their stability. The work covers alpha, beta and gamma decay, decay equations, half-life and decay rate, along with radiation safety and medical applications such as imaging, radiotherapy and tracers.
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1,254 questions · page 20 of 63
- A. 2.53 x 10^21
- B. 3.53 x 10^21
- C. 4.53 x 10^21
- D. 5.53 x 10^21
Explanation: Number of moles = 1/238. Number of nuclei = (1/238) × 6.022 × 1023 ≈ 2.53 × 1021.
Correct answer: 2.53 x 10^21- A. 2 x 10^5
- B. 4 x 10^5
- C. 6 x 10^5
- D. 8 x 10^5
Explanation: Number of half-lives = 15/5 = 3. Remaining atoms N = N0 × (1/2)3 = 1.6 × 106 × 1/8 = 2 × 105.
Correct answer: 2 x 10^5- A. 99.12 MeV
- B. 148.68 MeV
- C. 198.24 MeV
- D. 247.80 MeV
Explanation: Total binding energy = A × binding energy per nucleon = 24 × 8.26 = 198.24 MeV.
Correct answer: 198.24 MeV- A. 4.08 MeV
- B. 5.08 MeV
- C. 6.08 MeV
- D. 7.08 MeV
Explanation: Q. value = [m(90Th232) - ( m(88Ra228) +m(2He4)] × 931.5 = [232.0381 - 228.0311 + 4.0026] × 931.5 = 0.0044 × 931.5 ≈ 4.08 MeV.
Correct answer: 4.08 MeV- A. 3 hours
- B. 4 hours
- C. 6 hours
- D. 8 hours
Explanation: Activity A = A0 × (1/2)(t/T1/2). Given 80/640 = 1/8 = (1/2)3, so 3 = 12/T1/2 , T1/2 = 12/3 = 4 hours.
Correct answer: 4 hours- A. 2 x 10^4s
- B. 3 x 10^4s
- C. 4 x 10^4s
- D. 5 x 10^4s
Explanation: Half. life T1/2 = ln(2)/λ = 0.693/(2.31 × 105) ≈ 3 × 104s.
Correct answer: 3 x 10^4s- A. 2.56 x 10^24
- B. 2.66 x 10^24
- C. 2.76 x 10^24
- D. 2.86 x 10^24
Explanation: Energy per fission = 200 × 1.6 × 1013 = 3.2 × 1011 J. Number of fissions = 8.2 × 1013 / (3.2 × 1011 ) ≈ 2.56 × 1024.
Correct answer: 2.56 x 10^24- A. 7.7 MeV
- B. 8.7 MeV
- C. 9.7 MeV
- D. 10.7 MeV
Explanation: Binding energy per nucleon = total binding energy / A = 115.5/15 = 7.7 MeV.
Correct answer: 8.7 MeV- A. Endothermic
- B. Exothermic
- C. Neutral
- D. Forbidden
Explanation: A positive Q. value (0.546 MeV) indicates energy is released, making the reaction exothermic.
Correct answer: Exothermic- A. 2 days
- B. 3 days
- C. 4 days
- D. 5 days
Explanation: % remaining 50%→ 25%→ 12.5 %for 25% remaining =2 half lifefor 20% remaining = 8 days(given)i.e.
Correct answer: 3 days- A. 15.6 MeV
- B. 16.6 MeV
- C. 17.6 MeV
- D. 18.6 MeV
Explanation: Q. value = [m(1H2) + m(1H3) . m(2He4) . m(0n1)] × 931.5 = [2.0141 + 3.0160 - (4.0026 + 1.0087)] × 931.5 = 0.0188 × 931.5 ≈ 17.6 MeV.
Correct answer: 17.6 MeV- A. It has the highest number of protons
- B. It has the highest binding energy per nucleon
- C. It undergoes spontaneous fission
- D. It has equal numbers of protons and neutrons
Explanation: 26Fe56 has one of the highest binding energies per nucleon (~8.79 MeV), indicating strong nuclear stability.
Correct answer: It has the highest binding energy per nucleon- A. Positron
- B. Neutron
- C. Antineutrino
- D. Photon
Explanation: In beta. minus decay, a neutron decays into a proton, an electron, and an antineutrino (ν ̅ ).
Correct answer: Antineutrino- A. The change in atomic number
- B. The Q. value of the reaction
- C. The number of neutrons emitted
- D. The temperature of the nucleus
Explanation: The Q. value, the energy released or absorbed in a nuclear reaction, determines its nature. A positive Q.
Correct answer: The Q. value of the reaction- A. Alpha decay increases the neutron to proton ratio
- B. Alpha decay reduces the Coulomb repulsion in the nucleus
- C. Alpha decay emits more energy than beta decay
- D. Alpha decay involves weaker nuclear forces
Explanation: Heavy nuclei have high proton numbers, leading to strong Coulomb repulsion.
Correct answer: Alpha decay reduces the Coulomb repulsion in the nucleus- A. It repels protons to prevent collapse
- B. It binds nucleons together against Coulomb repulsion
- C. It causes radioactive decay
- D. It balances the gravitational force
Explanation: The strong nuclear force, a short-range attractive force, binds protons and neutrons (nucleons) together, overcoming the repulsive…
Correct answer: It binds nucleons together against Coulomb repulsion- A. Neutrons are positively charged and attract nuclei
- B. Neutrons have no charge and can penetrate nuclei easily
- C. Neutrons are lighter than protons
- D. Neutrons increase the binding energy of the nucleus
Explanation: Neutrons, being uncharged, are not repelled by the positive charge of the nucleus, allowing them to penetrate and interact with the…
Correct answer: Neutrons have no charge and can penetrate nuclei easily- A. Both increase
- B. Both decrease
- C. Both remain unchanged
- D. Mass number decreases, atomic number increases
Explanation: Gamma decay involves the emission of a high-energy photon from an excited nucleus, releasing energy without altering the number of protons…
Correct answer: Both remain unchanged- A. Increased neutron excess reduces stability
- B. Coulomb repulsion between protons increases
- C. The strong nuclear force becomes stronger
- D. The nucleus has fewer nucleons
Explanation: In heavy nuclei, the large number of protons increases Coulomb repulsion, which weakens the net binding effect of the strong nuclear…
Correct answer: Coulomb repulsion between protons increases- A. The reaction is spontaneous
- B. The reaction requires external energy
- C. The reaction produces no energy
- D. The reaction violates conservation laws
Explanation: A negative Q value indicates that the mass of the products is greater than the reactants, requiring external energy input to drive the…
Correct answer: The reaction requires external energy