Question

The mean life of a certain radioactive element is 6 hours, by what fraction will its initial activity decrease over a time period of 5 hours?

Answer 1

Dear Student,

◆ Answer -

0.5654

● Explaination -

Radioactive decay constant of element is given by -

λ = 1/τ

λ = 1/6 h⁻¹

Let A0 be initial activity of radioactive element. After 5 h its activity is given by -

A = A0.e^(-t.λ)

A = A0.e^(-5×1/6)

A = A0.e^(-5/6)

A = A0 × 0.4346

A = 0.4346A0

Fraction by which activity is decreased is -

∆A/A0 = (A-A0)/A0

∆A/A0 = (0.4346A0-A0)/A0

∆A/A0 = -0.5654

Therefore, initial activity of element will decrease by 0.5654 fraction after 5 hours.

Thanks dear...