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JEE Main 18 March 2021, Shift 1, Physics Q11

Question 11 of 90 in this shift, Physics question 11 of 30, Section A.

A radioactive sample disintegrates via two independent decay processes having half lives

T_{1/2}^{(1)}

and

T_{1/2}^{(2)}

respectively. The effective half-life,

T_{1/2}

of the nuclei is :

(1) $T_{1/2} = \frac{T_{1/2}^{(1)}\,T_{1/2}^{(2)}}{T_{1/2}^{(1)} + T_{1/2}^{(2)}}$ Official answer
(2) $T_{1/2} = T_{1/2}^{(1)} + T_{1/2}^{(2)}$
(3) $T_{1/2} = \frac{T_{1/2}^{(1)} + T_{1/2}^{(2)}}{T_{1/2}^{(1)} - T_{1/2}^{(2)}}$
(4)None of the above

Official answer

Option 1

NTA final key.

Chapter: Nuclei
Topic: Radioactive Decay
Idea tested: Parallel Decay Branching

Same topic in other shifts

All Radioactive Decay questions

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.