Question

Strontium-90 has a half-life of 29 years. In how many years will a 1 kg sample of strontium-90 decay and reduce to 0.25 kg of strontium-90?

Answer 1

58 years.
1kg - 0 years
0.5kg - 29 years
0.25kg - 58 years

Answer 2

The weight of Strontium-90 will reduce to
`0.25` Kg in
`58` years.

Step-by-step explanation:

Given -

Radioactive isotope sample of Strontium-90
`= 1`Kg

Half life of Strontium-90
`= 29` years

After first half life (i.e 29 years), the weight of Strontium-90

`= (1)/(2)\\= 0.5` Kg

After second half life (i.e 58 years), the weight of Strontium-90

`= (0.5)/(2)\\= 0.25` Kg

Thus, the weight of Strontium-90 will reduce to
`0.25` Kg in
`58` years.