Question

The half-life of krypton-91 is 10 seconds. At time t = 0 a heavy canister contains 3 g of this radioactive gas. How much remains after one minute?

Answer 1

Half time of krypton 91 = 10s

this means, it reduces to half of the remaining in every 10s

So, In 10 sec , the mass remaining will be :

3/2 = 1.5

After 20 sec, the mass remaining will be :

0.75 g

After 30 sec, the mass remaining will be :

0.375

After 40 sec, the mass remaining will be :

0.1875 g

After 50 sec, the mass remaining will be :

0.09375 g

After 1 minute, the mass remaining will be:

0.046975 g