Multiple Choices Questions (MCQ) on Half-Life in Physics

Half-life is a fundamental concept in physics that describes the time required for half of the nuclei in a radioactive sample to decay. Understanding half-life is essential for grade 12 students as it forms the basis for interpreting radioactive decay processes, calculating remaining quantities of isotopes over time, and applying this knowledge to real-world contexts such as radiocarbon dating and nuclear medicine. The questions provided above cover key aspects of half-life, from its definition and mathematical relationships to practical applications and problem-solving. 



By carefully studying these questions and their answer choices, students can reinforce their grasp of the concept, practice critical thinking, and enhance their readiness for national examinations. Engaging with these multiple-choice questions will help students confidently analyze decay problems, interpret half-life data, and apply formulas accurately—skills that are crucial for success in physics assessments.

How to answer the questions 
  1.  Select the options by clicking on the radio button 
  2.  Click on VIEW MY SCORE button at the end of the questions to view your results. 
  3.  If you made  mistake (s), you can try answer them again. 
All the best
 

1. What is the half-life of a radioactive substance?

A. The time it takes for a radioactive substance to completely decay
B. The time it takes for half the atoms in a substance to double
C. The time required for half the nuclei in a sample of a radioactive isotope to decay
D. The time it takes for a radioactive substance to emit all its radiation

2. What happens to the number of radioactive nuclei after one half-life?

A. It doubles.
B. It reduces to half.
C. It reduces to one quarter.
D. It remains the same.

3. The half-life of a radioactive isotope is 4 hours. How much of a 16 gram sample remains after 8 hours?

A. 8 grams
B. 4 grams
C. 2 grams
D. 1 gram

4. If the half-life of a substance is 10 minutes, what fraction remains after 30 minutes?

A. 1/2
B. 1/3
C. 1/8
D. 1/4

5. The half-life of Carbon-14 is approximately 5730 years. This is mainly used in:

A. Radiocarbon dating of archaeological samples
B. Medical imaging
C. Nuclear power generation
D. Sterilization of food

6. The decay constant (λ) is related to the half-life (T½) by which equation?





7. After three half-lives, what fraction of the original radioactive nuclei remain?

A. 1/3
B. 1/8
C. 1/6
D. 1/4

8. Which of the following best describes the half-life of a radioactive isotope?

A. It is a constant for each isotope, independent of the amount and conditions.
B. It changes depending on temperature.
C. It depends on the pressure applied to the substance.
D. It varies with the chemical state of the isotope.

9. A sample has a half-life of 5 years. How long will it take for 1/16 of the original amount to remain?

A. 5 years
B. 10 years
C. 20 years
D. 25 years

10. Which of these is NOT a use of half-life in science?

A. Dating ancient artifacts
B. Measuring the age of rocks
C. Determining the rate of radioactive decay
D. Measuring sound wave frequency

11. A radioactive isotope has a half-life of 1 hour. After 4 hours, what percentage of the original sample remains?

A. 25%
B. 50%
C. 6.25%
D. 12.5%

12. If a substance's half-life is very short, this means:

A. It is very stable.
B. It decays quickly.
C. It emits low energy radiation.
D. It has a large number of nuclei.

13. The activity of a radioactive sample is the number of decays per unit time. How does activity relate to half-life?

A. Shorter half-life means higher activity.
B. Longer half-life means higher activity.
C. Half-life does not affect activity.
D. Activity is only affected by temperature.

14. What is the half-life of a substance if after 10 hours only 25% of it remains?

A. 10 hours
B. 5 hours
C. 20 hours
D. 2.5 hours

15. If a radioactive substance has a half-life of 10 years, how much of a 100 g sample remains after 30 years?





16. Which factor does NOT influence the half-life of a radioactive isotope?

A. Chemical state
B. Physical state (solid, liquid, gas)
C. Environmental temperature
D. Nuclear properties

17. Which of these best represents the meaning of "half-life" in nuclear physics?

A. Time for half the atomic nuclei to decay
B. Time for all radioactive material to disappear
C. Time it takes for a substance to lose half its mass
D. Time required for half the radiation to be emitted

18. A sample has a half-life of 2 days. How much of a 100 g sample remains after 6 days?

A. 50 grams
B. 25 grams
C. 12.5 grams
D. 6.25 grams

19. The half-life concept is important in which of the following?

A. Calculating speed of light
B. Understanding radioactive decay
C. Measuring electrical resistance
D. Calculating kinetic energy

20. If the half-life of a radioactive isotope is known, what can be determined?

A. The isotope's chemical properties
B. The isotope's melting point
C. The isotope's atomic number
D. The rate at which it decays over time

Also check out
Previous Post Next Post

Advertisement