Quiz  /  Half Life Class 8 MCQ Questions With Answers

  • 1. 
    The process of nuclear change in an atom of radioactive material is called...

  • nuclear decay
  • nuclear mass
  • isotopes
  • radon

  • 2. 
    The solid black sections of the bars on the graph represent the percentages of

  • carbon-14 from the original sample that has not decayed
  • lead-206 decay product resulting from the radioactive decay
  • nitrogen-14 decay product resulting from the radioactive decay
  • uranium-238 from the original sample that has not decayed

  • 3. 
    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

  • 4. 
    After 22,800 years, approximately what percentage of the original carbon-14 remains?

  • 15%
  • 12.5%
  • 6.25%
  • 3.125%

  • 5. 
    "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

  • 6. 
    The radioactive surgery used in archaeology to date organic remains is...

  • C-12
  • U-238
  • C-14
  • U-235

  • 7. 
    A sample of wood that originally contained 100 grams of carbon-14 now contains only 25 grams of carbon-14. Approximately how many years ago was this sample part of a living tree?

  • 2,850 years
  • 5,700 years
  • 11,400 years
  • 17,100 years

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

  • 1
  • 2
  • 3
  • 4

  • 9. 
    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

  • 10. 
    Which radioactive element is used to determine the absolute age of late Pleistocene animal remains?

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

  • 11. 
    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

  • 12. 
    Radioactive carbon-14 is often useful in determining the absolute age of geologic samples because radioactive isotopes

  • decay at a regular rate
  • become less stable during decay
  • remain unchanged over time
  • stabilize after four half-lives

  • 13. 
    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

  • 14. 
    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

  • 15. 
    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

  • 16. 
    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

  • 17. 
    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.

  • 18. 
    A bone sample contains only 1/4 of its original radioactive C14 content. How old is the bone sample?

  • 1 C14 half-life
  • 2 C14 half-lives
  • 3 C14 half-lives
  • 4 C14 half-lives

  • 19. 
    Uranium has two isotopes but only one of them is radioactive. Which one?

  • U-235
  • U-238

  • 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
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