Half-Life Calculations
Chemistry ⇒ Nuclear Chemistry
Half-Life Calculations starts at 11 and continues till grade 12.
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See sample questions for grade 11
A 400 g sample of a radioactive isotope decays to 50 g in a certain period. How many half-lives have passed?
After 4 half-lives, what fraction of a radioactive sample remains?
Describe how you would determine the half-life of a radioactive isotope experimentally.
Explain the difference between half-life and mean life of a radioactive isotope.
A 10 g sample of a radioactive isotope decays to 2.5 g in 6 hours. What is the half-life of the isotope?
A 120 g sample of a radioactive isotope decays to 15 g in 4 half-lives. What is the mass remaining after 2 half-lives?
A 200 g sample of a radioactive isotope decays to 25 g in 3 days. What is the half-life of the isotope?
A 400 g sample of a radioactive isotope decays to 50 g in a certain period. How many half-lives have passed?
If a radioactive sample decays to 10% of its original amount, approximately how many half-lives have passed? (1) 2 (2) 3 (3) 4 (4) Between 3 and 4
If a radioactive substance has a half-life of 5 hours, what fraction of the original sample remains after 15 hours? (1) 1/2 (2) 1/4 (3) 1/8 (4) 1/16
If the half-life of a substance is 4 years, what percentage of the original sample remains after 8 years? (1) 25% (2) 50% (3) 75% (4) 12.5%
Which equation is used to calculate the remaining amount of a radioactive substance after a given time? (1) N = N₀ × (1/2)^(t/T₁/₂) (2) N = N₀ × t/T₁/₂ (3) N = N₀ × 2^(t/T₁/₂) (4) N = N₀ × e^(t/T₁/₂)
Fill in the blank: After one half-life, the amount of radioactive substance remaining is _______ of the original amount.
Fill in the blank: The half-life of a radioactive isotope is the time taken for _______ of the radioactive atoms to decay.
Fill in the blank: The mathematical relationship for the number of undecayed nuclei N after time t is N = N₀ × (1/2)^(t/______).
The half-life of carbon-14 is approximately _______ years.
Is the half-life of a radioactive isotope affected by temperature or pressure? (Yes/No)
True or False: After two half-lives, 75% of the original radioactive sample has decayed.
True or False: The half-life of a radioactive isotope depends on the amount of substance present.
True or False: The rate of radioactive decay increases as the sample gets smaller.
