Half-Life Calculations-More Practice

Front

What is half-life?

Back

Half-life is the time required for half of the radioactive atoms in a sample to decay.

Front

If the half-life of a substance is 2.4 minutes, how much of a 100g sample remains after 2.4 minutes?

Back

50g remains after 2.4 minutes.

Front

How do you calculate the initial amount (M_i) needed for a specific time given the half-life?

Back

Use the formula M_i = M_f * (2^(t/T_half)), where M_f is the final amount, t is the total time, and T_half is the half-life.

Front

What fraction of a sample remains after 3 half-lives?

Back

1/8 of the original sample remains after 3 half-lives.

Front

If a radioisotope has a half-life of 10 minutes, how much will remain after 30 minutes?

Back

1/8 of the original amount will remain after 30 minutes.

Front

What is the relationship between half-life and decay constant (λ)?

Back

The decay constant is related to half-life by the formula λ = ln(2) / T_half.

Front

How long will it take for a substance with a half-life of 5 years to decay to 1/16 of its original amount?

Back

It will take 20 years to decay to 1/16 of its original amount.

Front

What is the remaining percentage of a radioactive sample after 2 half-lives?

Back

25% of the original sample remains after 2 half-lives.

Front

If you start with 80g of a substance with a half-life of 4 hours, how much will remain after 12 hours?

Back

10g will remain after 12 hours.

Front

What is the formula to calculate the remaining mass after a certain time?

Back

Remaining mass = Initial mass * (1/2)^(time elapsed / half-life).