What is the halflife of a radioisotope if a 20-g sample becomes 10g after 16 hours

T½ = 16hours

Explanation:

Final mass (N) = 10g

Initial mass (No) = 20g

Time (t) = 16hours

T½ = ?

T½ = In2 / λ

But λ = ?

In (N/No) = - λt

In (10/20) = - (λ * 16)

In (0.5) = - 16λ

-0.693 = - 16λ

λ = 0.693 / 16

λ = 0.0433

Note : λ is known as the disintegration constant

T½ = In2 / λ

T½ = 0.693 / 0.0433

T½ = 16hours

The half-life of the sample is 16hours