JEE Main 2020 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 3 September 2020, Shift 1, Physics Q19

Question 19 of 75 in this shift, Physics question 19 of 25.

In a radioactive material, fraction of active material remaining after time t is 9/16. The fraction that was remaining after t/2 is :

(1) $\frac{3}{5}$
(2) $\frac{3}{4}$ Official answer
(3) $\frac{4}{5}$
(4) $\frac{7}{8}$

Official answer

Option 2

NTA final key (Sep 2020).

Chapter: Nuclei
Topic: Radioactive Decay
Idea tested: Statistical Decay Law

Same idea in other shifts

Asked 5× in all

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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 108 of the 174 JEE Main shifts held from 2017 to 2026.