About this Quiz

This Half Life Class 8 MCQ test contains random 30 Objective Questions. You have select one correct answer among given options.

Half Life Class 8 MCQ With Answers

1. Uranium has two isotopes but only one of them is radioactive. Which one?

  • U-235
  • U-238

2. A sample of Radium-228 decays from 100g to 12.5g. How many half lives did it experience?

  • 1
  • 2
  • 3
  • 4

3. The radioactive surgery used in archaeology to date organic remains is...

  • C-12
  • U-238
  • C-14
  • U-235

4. The radioactive isotope Nickel-63 has a half life of 100 years. How much of a 10 gram sample remains after 300 years?

  • 1 gram
  • 1.25 grams
  • 0.50 grams
  • 0.075 grams

5. Those patients who develop tyroid cancer are treated with a certain radioactive isotope before attending surgery. The isotope is ...

  • As-74
  • Tc-99
  • I-131
  • Na-24

6. Which diagram best represents the percentage of this radioactive isotope sample that will remain after 2 half-lives?

7. Uranium has two isotopes but only one of them is radioactive. Which one?

  • U-235
  • U-238

8. A sample of Radium-228 decays from 100g to 12.5g. How many half lives did it experience?

  • 1
  • 2
  • 3
  • 4

9. The half-life of Iodine-131 is 8 days. What does this mean?

  • The lifespan of Iodine-131 is 8 days
  • Iodine-131 takes 8 days to become a radioactive material
  • Iodine-131 takes 8 days to decay to half the amount of its original amount
  • Iodine-131 takes days to become a non-radioactive material

10. According to the law of superposition, the oldest fossils are found 

  • At the top of the rock layers
  • Near the bottom of the rock layers
  • In the middle of the rock layers
  • Somewhat near the surface

11. Those patients who develop tyroid cancer are treated with a certain radioactive isotope before attending surgery. The isotope is ...

  • As-74
  • Tc-99
  • I-131
  • Na-24

12. Which radioactive element is used to determine the absolute age of late Pleistocene animal remains?

  • rubidium-87
  • uranium-238
  • potassium-40
  • carbon-14

13. "A random and spontaneous process where an unstable nucleus emits radioactive radiation until the nucleus becomes more stable.."The statement above refer to...

  • Half -life
  • Nuclei decay
  • Radioactivity
  • Radioactive decay

14. The process of nuclear change in an atom of radioactive material is called... 

  • nuclear decay
  • nuclear mass
  • isotopes
  • radon

15. The most dreadful accident involving a Nuclear Power Plant happened in 1986 in...

  • Kiev
  • Chernobyl

16. How much of an 800-gram sample of potassium-40 will remain after 3.9 × 10^9 years of radioactive decay?

  • 50 grams
  • 100 grams
  • 200 grams
  • 400 grams

17. The unit of activity is ____________.

  • rutherford
  • Becquerel
  • Both A & B
  • None of these

18. Radioactive decay of 40K atoms in an igneous rock has resulted in a ratio of 25 percent 40K atoms to 75 percent. 40Ar and 40Ca atoms. How many years old is this rock?

  • 0.3 x 10^9 years
  • 1.3 x 10^9 years
  • 2.6 x 10^9 years
  • 3.9 x 10^9 years

19. An alpha source in a smoke detector should have a _____ half-life.

  • long

20. The radioactive isotope Nickel-63 has a half life of 100 years. How much of a 10 gram sample remains after 300 years?

  • 1 gram
  • 1.25 grams
  • 0.50 grams
  • 0.075 grams

21. When and where were dropped the first two atomic bombs by US forces?

  • In 1945 over the Japanese cities of Hiroshima and Tokyo
  • In 1942 over the Japanese cities of Nagasaki and Tokyo
  • In 1942 over the Japanese cities of Hiroshima and Nagasaki
  • In 1945 over the Japanase cities of Hiroshima and Nagasaki

22. The activity of a sample is 640 Bq. It's half-life is 3 hours. Calculate the percentage of activity remaining after 6 hours.

  • 25%
  • 25

23. If one has 12 kg of Polonium and it undergoes two half-lives, how much do you have left?

  • 12 kg
  • 3 kg
  • 6 kg
  • None of these

24. When is the rate of radioactive decay the fastest?

  • end
  • beginning
  • middle
  • None of these

25. Calculate the activity of the sample after 3 half-lives.

  • 10 Bq
  • 10
  • 10 cpm
  • 10 counts per minute
  • 10 Becquerels

26. A radioactive isotope has a half-life of 3 days. It's current activity 52 Bq. Calculate its activity 9 days ago.

  • 416 Bq
  • 416

27. "A random and spontaneous process where an unstable nucleus emits radioactive radiation until the nucleus becomes more stable.."The statement above refer to...

  • Half -life
  • Nuclei decay
  • Radioactivity
  • Radioactive decay

28. The initial activity of a sample is 600 Bq. Calculate the percentage reduction in activity after 3 half-lives

  • 87.5%
  • 87.5

29. Select the correction definition for half-life.

  • The time it takes for all of the radioactive nuclei to decay.
  • The time it takes for half of the radioactive nuclei to decay.
  • Half the time it takes for all of the radioactive nuclei to decay.
  • Half the time it takes for half of the radioactive nuclei to decay.

30. Iodine-131 has a half life of 8.07 days. What fraction of a sample of Iodine-131 is left unchanged after 16.14 days?

  • 1/2
  • 1/4
  • 1/8
  • 1/16

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