Half Life Decay

Front

What is half-life?

Back

Half-life is the time required for a quantity to reduce to half its initial amount, commonly used in the context of radioactive decay.

Front

If a substance has a half-life of 10 years, how much of a 100 g sample remains after 20 years?

Back

25 g (after 2 half-lives: 100g -> 50g -> 25g).

Front

What happens to the amount of a radioactive substance after each half-life?

Back

The amount of the substance decreases by half after each half-life.

Front

How many half-lives are needed for a substance to decay from 80 g to 10 g if its half-life is 5 years?

Back

3 half-lives (80g -> 40g -> 20g -> 10g).

Front

What is the formula to calculate the remaining quantity of a substance after a certain number of half-lives?

Back

Remaining quantity = Initial quantity × (1/2)^(number of half-lives).

Front

If the half-life of a substance is 15 minutes, how long will it take for it to decay completely after 5 half-lives?

Back

75 minutes (5 half-lives × 15 minutes each).

Front

What is radioactive decay?

Back

Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation.

Front

If a sample of carbon-14 has a half-life of 5730 years, how much of a 12 g sample remains after 11460 years?

Back

3 g (after 2 half-lives: 12g -> 6g -> 3g).

Front

What is the significance of half-life in carbon dating?

Back

Half-life is used in carbon dating to determine the age of organic materials by measuring the remaining carbon-14.

Front

If a radioactive isotope has a half-life of 2 hours, how much of a 64 g sample will remain after 6 hours?

Back

8 g (after 3 half-lives: 64g -> 32g -> 16g -> 8g).