What is the average life of a radioactive element whose half-life is 30 days?

Correct option is D

Correct option: (d) 43.29 days
Explanation (step-by-step):
· Average life (mean life, τ) of a radioactive element is related to half-life ( t₁/₂) by:

Hence, the average life = 43.29 days.
❌ Why other options are incorrect
· (a) 60.03 – Overestimation; does not follow the mean-life relation.
· (b) 15.21 – Approximately half of the half-life; conceptually incorrect.
· (c) 20.79 – About two-thirds of half-life; not a valid radioactive parameter.
�� Key Points to Remember
· Mean (average) life (τ) = t₁/₂ / 0.693
· Mean life is always greater than half-life.
· Commonly used in radioactive decay calculations.