Learn

Saturday, 31 October

JEE Main 2022 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 26 July 2022, Shift 1, Physics Q33

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

The disintegration rate of a certain radioactive sample at any instant is 4250 disintegrations per minute. 10 minutes later, the rate becomes 2250 disintegrations per minute. The approximate decay constant is : (Take log⁡101.88=0.274\log_{10}1.88 = 0.274)
  1. (1)0.02 min−10.02\ \mathrm{min^{-1}}
  2. (2)2.7 min−12.7\ \mathrm{min^{-1}}
  3. (3)0.063 min−10.063\ \mathrm{min^{-1}}Official answer
  4. (4)6.3 min−16.3\ \mathrm{min^{-1}}

Official answer

Option 3

NTA final key.

Chapter
Nuclei
Topic
Radioactive Decay
Idea tested
Activity and Rate of Decay

Same idea in other shifts

Asked 3× in all
  1. 10 Apr 2023, Shift 1 · Q56The decay constant for a radioactive nuclide is 1.5×10−5 s−11.5\times10^{-5}\,s^{-1}. Atomic weight of the substance is 60 g mole−1^{-1}, (…EasyNumerical value
  2. 16 Mar 2021, Shift 2 · Q12The half-life of Au198\mathrm{Au^{198}} is 2.7 days. The activity of 1.50 mg of Au198\mathrm{Au^{198}} if its atomic weight is 198 g…MediumSingle 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 108 of the 174 JEE Main shifts held from 2017 to 2026.