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.
Last updated
1,254 questions · page 19 of 63
- A. 5000 s
- B. 7500 s
- C. 10000 s
- D. 12500 s
Explanation: T 1/2 = 0.693/1.386 x 104 T 1/2= 5000 sFor 75% decay: 2 half life So, 5000 x 2 = 10000s
Correct answer: 10000 s- A. 1 x 10^5
- B. 2 x 10^5
- C. 3 x 10^5
- D. 4 x 10^5
Explanation: Number of half. lives = 36/12 = 3. Remaining atoms N = N0 × (1/2)n = 8 × 105 × (1/2)3 = 8 × 105 × 1/8 = 1 × 105.
Correct answer: 1 x 10^5- A. 64 MeV
- B. 96 MeV
- C. 128 MeV
- D. 160 MeV
Explanation: Total binding energy = A × binding energy per nucleon, where A = 16. Thus, 16 × 8.0 = 128 MeV.
Correct answer: 128 MeV364. A nucleus undergoes beta-minus decay: 14C6→ 14N7+ e-1. The Q. value is 0.156 MeV. The reaction is:
- A. Endothermic
- B. Exothermic
- C. Neutral
- D. Forbidden
Explanation: A positive Q. value (0.156 MeV) indicates energy is released, making the reaction exothermic.
Correct answer: Exothermic- A. 5 μCi
- B. 10 μCi
- C. 15 μCi
- D. 20 μCi
Explanation: After one half. life, activity A = A × (1/2) = 20 × 1/2 = 10 μCi.
Correct answer: 10 μCi- A. 1.39 x 10^6s
- B. 2.78 x 10^6s
- C. 3.47 x 10^6s
- D. 4.16 x 10^6s
Explanation: Half-life T1/2 = ln(2)/λ = 0.693/(5 × 107) ≈ 1.386 × 106s.
Correct answer: 1.39 x 10^6s- A. 7.81 x 10^23
- B. 1.56 x 10^24
- C. 2.34 x 10^24
- D. 3.12 x 10^24
Explanation: Energy per fission = 200 × 1.6 × 1013 = 3.2 × 1011 J. Number of fissions = total energy/energy per fission = 2.5 × 1010 / (3.2 × 1011) ≈…
Correct answer: 7.81 x 10^23- A. 4.27 MeV
- B. 5.27 MeV
- C. 6.27 MeV
- D. 7.27 MeV
Explanation: Q. value = [m(92U238) . m( 90Th234) . m(2 He4)] × 931.5 = [238.0508 - 234.0436 + 4.0026] × 931.5 = 0.0046 × 931.5 ≈ 4.27 MeV.
Correct answer: 4.27 MeV- A. 29.2 MeV
- B. 39.2 MeV
- C. 49.2 MeV
- D. 59.2 MeV
Explanation: Binding energy = mass defect × c2 = 0.0421 × 931.5 ≈ 39.2 MeV.
Correct answer: 39.2 MeV- A. Half-life of radioactive element
- B. Mean life
- C. Decay constant of radioactive element
- D. Activity of radioactive element
Explanation: Rate of decay ÷ number of nuclei = λ, which is the decay constant. It represents the probability per unit time that a nucleus will decay.
Correct answer: Decay constant of radioactive element- A. 2.27 MeV
- B. 3.27 MeV
- C. 4.27 MeV
- D. 5.27 MeV
Explanation: Q. value = [2m(1H2) . m(2He3) . m(0n1)] × 931.5 = [2 × 2.0141 - ( 3.0160 + 1.0087)] × 931.5 = 0.0035 × 931.5 ≈ 3.27 MeV.
Correct answer: 3.27 MeV- A. 2 hours
- B. 3 hours
- C. 4 hours
- D. 6 hours
Explanation: 1000 →500→ 250 →125 3 half-life →12 hours1 half-life →12/3 hours= 4 hours.
Correct answer: 4 hours- A. 80.3 MeV
- B. 120.45 MeV
- C. 160.6 MeV
- D. 200.75 MeV
Explanation: Total binding energy = A × binding energy per nucleon = 20 × 8.03 = 160.6 MeV.
Correct answer: 160.6 MeV- A. ΔA = 0, ΔZ = 0
- B. ΔA = 1, ΔZ = 0
- C. ΔA = 0, ΔZ = 1
- D. ΔA = 4, ΔZ = 2
Explanation: Gamma decay releases energy as a photon without changing the nucleus's mass number (A) or atomic number (Z).
Correct answer: ΔA = 0, ΔZ = 0- A. 16.6 days
- B. 21.6 days
- C. 26.6 days
- D. 31.6 days
Explanation: Time = half-life x number of half-lives For 90% decay:- After 1 half-life, 50% remains- After 3 half-lives, 12.5% remains- After 3.32…
Correct answer: 26.6 days376. The energy released in the beta plus decay 22Na11 → 22Ne10 + 0e+1 is 0.543 MeV. The reaction is:
- A. Endothermic
- B. Exothermic
- C. Neutral
- D. Forbidden
Explanation: A positive Q. value (0.543 MeV) indicates energy release, making the reaction exothermic.
Correct answer: Exothermic- A. 241.9 MeV
- B. 291.9 MeV
- C. 341.9 MeV
- D. 391.9 MeV
Explanation: Binding energy= mass defect× c2 =0.3672× 931.5 ≈341.9 MeV.
Correct answer: 341.9 MeV- A. 15000 s
- B. 20000 s
- C. 25000 s
- D. 30000 s
Explanation: For 50% decay, T1/2 = ln(2)/λ = 0.693/(2.31 × 105) ≈ 30000 s.
Correct answer: 30000 s- A. 2:3
- B. 3:2
- C. 2:1
- D. 3:1
Explanation: By conservation of momentum, m1 v1 = m2 v2 . Kinetic energy KE = (1/2)mv2 , so KE1 /KE2 = (m1v12)/(m2v22) = 3/2.
Correct answer: 2:3- A. Endothermic
- B. Exothermic
- C. Neutral
- D. Forbidden
Explanation: A negative Q. value (0.93 MeV) indicates energy is absorbed, making the reaction endothermic.
Correct answer: Endothermic