Quiz  /  Half Life Class 10 MCQ Questions With Answers

  • 1. 
    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

  • 2. 
    After 22,800 years, approximately what percentage of the original carbon-14 remains?

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

  • 3. 
    Which radioactive element is used to determine the absolute age of late Pleistocene animal remains?

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

  • 4. 
    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

  • 5. 
    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

  • 6. 
    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.

  • 7. 
    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

  • 8. 
    Gamma rays have

  • no mass
  • a huge mass
  • a small mass
  • an average mass

  • 9. 
    What is the only difference between two different isotopes of the same element?

  • Number of neutrons
  • Number of protons
  • Number of electrons
  • Size of atom

  • 10. 
    If the half-life of uranium-232 is 70 years, how many half-lives will it take for 10 g of it to be reduced to 1.25 g?

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

  • 11. 
    After the third half-life, how much of a radioactive sample is left?

  • 1/2
  • 1/3
  • 1/16
  • 1/8

  • 12. 
    The diagram shows 32 atoms32 of the Red are the parent isotope 0 of the atoms are daughter isotopes How many half-lives have occurred?

  • 0
  • 1
  • 2
  • 3

  • 13. 
    As a sample of Neon-19 undergoes radioactive decay, its half-life will

  • decrease
  • increase
  • remain the same
  • start over

  • 14. 
    How many half-live will Ca-37 go through in 1092 ms?

  • 1
  • 3
  • 6
  • 9

  • 15. 
    This is the correct equation for U-238 decay.

  • true
  • false

  • 16. 
    Which isotope has a half-life of 5715 years?

  • Carbon-12
  • Cobalt-60
  • Carbon-14
  • Cesium-137

  • 17. 
    How much time must pass for Hydrogen-3 to undergo 3 half-lives?

  • 12.31 years
  • 36.93 years
  • 4.10 years
  • 3.00 years

  • 18. 
    Which of the following samples would have the greatest amount remaining after 28 days?

  • 5g of Au-198
  • 10g of I-131
  • 5g of P-32
  • 10g of Rn-222

  • 19. 
    The half-life of strontium-90 is 25 years. How much strontium-90 was originally present if 0.25 g is present in a sample after 100 years?

  • 4.0 g
  • 2.0 g
  • 0.13 g
  • 0.25 g

  • 20. 
    An isotope of cesium (cesium-137) has a half-life of 30 years. If 1.0 mg of cesium-137 disintegrates over a period of 90 years, how many mg of cesium-137 would remain?

  • 0.5 mg
  • 0.25 mg
  • 0.125 mg
  • 0.0625 mg

  • 21. 
    What type of decay is being illustrated in following picture?

  • beta decay
  • alpha decay

  • 22. 
    The half life of an element is 20 minutes.  What % of the element remains after an hour?

  • 0%
  • 12.5%
  • 20%
  • 25%

  • 23. 
    An isotope of silver has a half-life of 10 minutes. What fraction of the original mass would remain after one hour?

  • 1/64
  • 1/2
  • 1/4
  • 1/8

  • 24. 
    Barium-122 has a half-life of 2 minutes. A fresh sample weighing 80.0 g was obtained. If it takes 10 minutes to set up an experiment using barium-122, how much barium-122 will be left when the experiment begins?

  • 0.250 g
  • 2.50 g
  • 25.0 g
  • 80.0 g

  • 25. 
    A 2.5 gram sample of an isotope of strontium-90 was formed in a 1960 explosion of an atomic bomb at Johnson Island in the Pacific Test Site. The half-life of strontium-90 is 28 years. In what year will only 0.625 grams of this strontium-90 remain?

  • 1988
  • 2016
  • 2044
  • 2072

  • 26. 
    This is the correct equation for the decay of Ra.

  • true
  • false
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