Question

The half life time of a radioactive elements of x is the same as the mean life of another radioactive element y. Initially they have same number of atoms, then

(A) y will decay faster then x 

(B) x will decay faster then y 

(C) x and y will decay at the same rate at all time 

(D) x and y will decay at the same rate initially.

Answer 1

The correct option is (A) y will decay faster then x.

Explanation:

Given : Half life time of x = mean life time of y

∴ T_(1/2)(x) = τ(y)

∴ [(0.693) / (λx)] = (1 / λy) ----- where λ is decay constant

∴ λy = [(λx) / (0.693)] i.e. λy = 1.44 λx

 i.e. λy > λx

Hence y will decay faster.