JEE Main 2022 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 29 June 2022, Shift 1, Physics Q33

Question 33 of 90 in this shift, Physics question 3 of 30, Section A.

The activity of a radioactive material is

2.56 \times 10^{-3}

Ci. If the half life of the material is 5 days, after how many days the activity will become

2 \times 10^{-5}

Ci ?

(1)30 days
(2)35 daysOfficial answer
(3)40 days
(4)25 days

Official answer

Option 2

NTA final key (2022 Session 1).

Chapter: Nuclei
Topic: Radioactive Decay
Idea tested: Half-Life Calculations

Same idea in other shifts

Asked 5× in all

8 Apr 2023, Shift 2 · Q44A radio active material is reduced to 1/8 of its original amount in 3 days. If $8\times10^{-3}$ kg of the material is left after 5 days…MediumSingle correct
3 Aug 2021, Shift 2 · Q18A radioactive isotope has a half life of T years. After how much time is its activity reduced to 6.25% of its original activity ?EasySingle correct
3 Aug 2021, Shift 2 · Q25A sample undergoing beta decay, reduced to $\frac{1}{16}^{\mathrm{th}}$ of its initial mass in 48 years. Its half life period is…EasyNumerical value
16 Mar 2021, Shift 2 · Q10Calculate the time interval between 33% decay and 67% decay if half-life of a substance is 20 minutes.EasySingle correct

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.