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Quiz Chapter 8: Radioactivity

10 questions · Form 3 Science Bab 8: Radioactivity

Question 1 of 10Score: 0

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

Full Question List & Answer Key

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

1. 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.

2. What device is worn by radiation workers to measure cumulative personal radiation exposure doses over time?

  1. Geiger-Müller counter
  2. Gold-leaf electroscope
  3. Film badge (dosimeter)
  4. Cathode ray oscilloscope
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Answer: C

A photographic film badge or dosimeter monitors cumulative ionizing radiation absorbed by personnel working near radioactive sources.

3. What happens to a beam of Beta (\beta) particles when passed through an electric field?

  1. Deflected towards the positive electric plate
  2. Deflected towards the negative electric plate
  3. Passes straight through without deflection
  4. Reflected back to the source
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Answer: A

Beta particles are high-speed negatively charged electrons ($^0_{-1}e$), so they are attracted toward the positive electric plate.

4. 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.

5. 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.

6. 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).

7. Which radioactive particle consists of a helium nucleus ($^4_2He$) carrying a +2 charge?

  1. Alpha particle
  2. Beta particle
  3. Gamma ray
  4. Neutron beam
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Answer: A

Alpha particles are helium nuclei composed of 2 protons and 2 neutrons with a net positive charge of +2.

8. Which radioactive isotope is commonly used in medicine for cancer radiotherapy treatment?

  1. Carbon-14
  2. Cobalt-60
  3. Sodium-24
  4. Phosphorus-32
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Answer: B

Cobalt-60 emits high-energy gamma rays used in radiotherapy to destroy cancerous tumor cells.

9. Which radioactive isotope is used by archeologists to estimate the age of ancient organic wood and bone fossils?

  1. Uranium-238
  2. Carbon-14
  3. Iodine-131
  4. Lead-206
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Answer: B

Carbon-14 radiocarbon dating measures remaining Carbon-14 activity in organic matter to determine fossil age up to ~50,000 years.

10. A radioactive sample has an initial activity of 800 Bq. If its half-life is 10 days, what will its activity be after 30 days?

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

Number of half-lives = 3010 = 3 half-lives. Activity drops: 800 -> 400 -> 200 -> 100 Bq.

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