Question

Sodium-24 has a half-life of 15 hours. If a sample of sodium-24 has an original activity of 500 Bq, what will its activity be after 30 hours?

Answer 1

The half-life is a period after that the activity becomes two times smaller, so after 15 hours the activity will be 500 Bq/2 = 250 Bq. After the next 15 hours activity will be 250 Bq/2 = 125 Bq, or the one fourth of the initial activity.