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Quiz Chapter 6: Nuclear Physics

10 questions · Form 5 Physics Bab 6: Nuclear Physics

Question 1 of 10Score: 0

Which of the following processes is the main source of thermal and radiant energy produced by the Sun?

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. Which of the following processes is the main source of thermal and radiant energy produced by the Sun?

  1. Nuclear Fission
  2. Nuclear Fusion
  3. Alpha Decay
  4. Chemical Combustion
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Answer: B

The Sun generates energy by fusing Hydrogen isotopes (Deuterium and Tritium) into Helium nuclei under massive gravitational pressure and heat.

2. Which equation correctly represents a nuclear fission reaction?

  1. ¹₄₆C -> ¹₄₇N + ⁰₋₁e
  2. ²₁H + ³₁H -> ⁴₂He + ¹₀n + Energy
  3. ²³⁵₉₂U + ¹₀n -> ¹₄¹₅₆Ba + ⁹²₃₆Kr + 3(¹₀n) + Energy
  4. ²²⁶₈₈Ra -> ²²²₈₆Rn + ⁴₂He
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Answer: C

Uranium-235 absorbing a neutron and splitting into Barium-141, Krypton-92, extra neutrons, and energy is a nuclear fission reaction.

3. If a sample of radioactive material decays from 80 g to 10 g in 45 minutes, what is its half-life?

  1. 15 minutes
  2. 22.5 minutes
  3. 30 minutes
  4. 10 minutes
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Answer: A

80g -> 40g (1) -> 20g (2) -> 10g (3 half-lives). Total time = 45 min, so T_{12} = 453 = 15 minutes.

4. Gamma radiation is unaffected by both electric and magnetic fields because:

  1. It travels faster than light
  2. It carries no electrical charge
  3. Its mass is extremely heavy
  4. It undergoes total internal reflection
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Answer: B

Gamma rays are high-frequency electromagnetic waves with zero electric charge and zero rest mass.

5. Convert 1.5 atomic mass units (u) into kilograms. (1 u = 1.66 × 10⁻²⁷ kg)

  1. 2.49 × 10⁻²7 kg
  2. 1.11 × 10⁻²7 kg
  3. 3.32 × 10⁻²7 kg
  4. 2.49 × 10⁻²⁹ kg
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Answer: A

1.5 × (1.66 × 10⁻²⁷ kg) = 2.49 × 10⁻²⁷ kg.

6. Which statement correctly describes the term 'spontaneous decay' in radioactivity?

  1. The decay rate can be accelerated by heating the sample
  2. It occurs naturally without being affected by external factors such as temperature or pressure
  3. It is possible to pinpoint the exact time an individual nucleus will decay
  4. It occurs only when bombarded by high-energy X-rays
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Answer: B

Spontaneous decay happens naturally and is totally unaffected by physical or chemical conditions.

7. When a Radon-222 nucleus ($^{222}_{86}Rn$) emits an alpha particle, what is the nucleon number and proton number of the daughter nucleus formed?

  1. Nucleon number = 218, Proton number = 84
  2. Nucleon number = 222, Proton number = 87
  3. Nucleon number = 218, Proton number = 85
  4. Nucleon number = 226, Proton number = 88
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Answer: A

Alpha emission removes 4 from nucleon number (222 - 4 = 218) and 2 from proton number (86 - 2 = 84).

8. Which sheet material is sufficient to completely stop alpha particles?

  1. A single sheet of paper
  2. 5 mm thick aluminium plate
  3. 10 cm thick concrete wall
  4. Lead container
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Answer: A

Alpha particles have low penetrating power and are absorbed by a thin sheet of paper.

9. An unstable isotope Carbon-14 ($^{14}_{6}C$) decays into Nitrogen-14 ($^{14}_{7}N$). What type of decay occurred?

  1. Alpha decay
  2. Beta decay
  3. Gamma emission
  4. Neutron emission
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Answer: B

Proton number increases by 1 (6 to 7) while nucleon number remains 14. This signifies beta emission ($^{0}_{-1}e$).

10. A radioactive isotope has a half-life of 6 hours. If its initial activity is 1600 Bq, what is its activity after 24 hours?

  1. 400 Bq
  2. 200 Bq
  3. 100 Bq
  4. 50 Bq
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Answer: C

Number of half-lives n = 246 = 4. Final activity = 1600 × (12)⁴ = 160016 = 100 Bq.

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