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Quiz Chapter 8: Radioactivity

10 questions · Form 3 Science Bab 8: Radioactivity

10 questions · plays in fullscreen

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 source contributes to NATURAL background radiation in our environment?

  1. Nuclear weapons testing fallout
  2. Diagnostic medical X-ray scans
  3. Radon gas from surrounding rocks and soil
  4. Radioactive waste from nuclear power plants
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Answer: C

Radon gas emitted naturally from soil and rocks containing uranium is a major natural source of background radiation.

2. A radioactive sample decays from 120 g to 15 g in 24 hours. What is the half-life of this isotope?

  1. 4 hours
  2. 6 hours
  3. 8 hours
  4. 12 hours
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Answer: C

120 g -> 60 g -> 30 g -> 15 g requires 3 half-lives. 3 half-lives = 24 hours, so 1 half-life = 243 = 8 hours.

3. How does a neutral atom transform into a positive ion (cation)?

  1. By gaining one or more protons
  2. By losing one or more electrons
  3. By gaining one or more electrons
  4. By losing neutrons from its nucleus
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Answer: B

A positive ion is formed when an atom loses negative electrons, resulting in more positive protons than negative electrons.

4. Which type of radioactive ray has the HIGHEST penetrating power and requires thick lead or concrete to stop it?

  1. Alpha particle
  2. Beta particle
  3. Gamma ray
  4. Cosmic ray
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Answer: C

Gamma rays are high-energy electromagnetic waves with no mass or charge, giving them extremely high penetrating power.

5. Who among the following scientists discovered radioactivity in 1896 using uranium compounds?

  1. Marie Curie
  2. Henri Becquerel
  3. Wilhelm Röntgen
  4. Ernest Rutherford
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Answer: B

Henri Becquerel discovered radioactivity in 1896 when uranium compounds spontaneously emitted rays that blackened photographic plates.

6. What unit is used to measure the biological dosage effect of background ionising radiation on human tissue?

  1. Joule (J)
  2. Sievert (Sv)
  3. Watt (W)
  4. Becquerel (Bq)
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Answer: B

The Sievert (Sv), or microSievert ($\μSv$), measures equivalent biological radiation dose absorbed by human bodies.

7. Which sheet material is sufficient to completely block and stop Alpha (α) particles?

  1. A piece of paper
  2. A thin aluminum plate
  3. A thick block of lead
  4. A reinforced concrete wall
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Answer: A

Alpha particles have low penetrating power and can be completely stopped by a simple piece of paper or human skin.

8. Which industry uses Beta radiation to monitor and regulate the uniform thickness of paper or aluminum sheets during production?

  1. Agricultural industry
  2. Manufacturing paper/foil mills
  3. Food preservation industry
  4. Geological mining
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Answer: B

Beta radiation passes through thin sheets; detectors read transmission levels to automatically adjust roller pressure for consistent thickness.

9. Which of the following is classified as NON-IONISING radiation?

  1. Gamma rays
  2. Alpha particles
  3. Microwaves
  4. X-rays
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Answer: C

Microwaves belong to non-ionising radiation on the electromagnetic spectrum, lacking sufficient energy to ionize atoms.

10. Which radiation particle has the HIGHEST ionising power?

  1. Gamma ray
  2. Beta particle
  3. Alpha particle
  4. X-ray
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Answer: C

Alpha particles have the highest ionising power due to their relatively large mass and double positive charge (+2).

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