Question

The half-life period of a radioactive element A is same as the mean life time of another radioactive element B. Initially both have the same number of atoms. Then 

(a) A and B have the same decay rate initially 

(b) A and B decay at the same rate always 

(c) B will decay at faster rate than A 

(d) A will decay at faster rate than B.

Answer 1

(c) B will decay at faster rate than A

(t _1/2)_A = (t _mean)_B

\(\frac{0.6931}{λ_A} = \frac{1}{λ_B}\)

λ_A = 0.6931 λ_B 

λ_A < λ_B