Q. The half life of a radioactive nucleus is 50 days. The time interval (t₂ − t₁) between the time t₂ when 2/3 of it has decayed and the time t₁ when 1/3 of it had decayed is
A) 30 days
B) 50 days
C) 60 days
D) 15 days
Explanation
[Solution from source] When 1/3 has decayed, 2/3 remains; when 2/3 has decayed, 1/3 remains. The undecayed amount halves between these instants, which takes exactly one half-life, 50 days. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.