Question

The half-life of the strontium-90 is 30 years. In how much time will 0.04 grams of strontium-90 be dissociated, leaving 0.005 grams?

Answer 1

If the half-life of Sr-90 is 25 years it means that after 25 years its amount will be half the initial quantity.

If you have 4,00 g, after 25 years you have 2,00 g;

after 50 years you have 1,00 g;

after 75 years you have 0,50 g;

after 100 years you have 0,25 g