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Saturday, 31 October

JEE Main 2022 · PhysicsMultiple choiceOtherMediumConceptual

JEE Main 28 June 2022, Shift 2, Physics Q48

Question 48 of 90 in this shift, Physics question 18 of 30, Section A.

Following statements related to radioactivity are given below : (A) Radioactivity is a random and spontaneous process and is dependent on physical and chemical conditions. (B) The number of un-decayed nuclei in the radioactive sample decays exponentially with time. (C) Slope of the graph of log⁡e\log_e (no. of undecayed nuclei) Vs. time represents the reciprocal of mean life time (τ\tau). (D) Product of decay constant (λ\lambda) and half-life time (T1/2T_{1/2}) is not constant. Choose the most appropriate answer from the options given below :
  1. (1)(A) and (B) only
  2. (2)(B) and (D) only
  3. (3)(B) and (C) onlyOfficial answer
  4. (4)(C) and (D) only

Official answer

Option 3

NTA final key.

Chapter
Nuclei
Topic
Radioactive Decay
Idea tested
Statistical Decay Law

Same idea in other shifts

Asked 5× in all
  1. 29 Jul 2022, Shift 2 · Q59Two radioactive materials A and B have decay constants 25λ25\lambda and 16λ16\lambda respectively. If initially they have the same number of…MediumNumerical value
  2. 25 Jul 2021, Shift 1 · Q5Some nuclei of a radioactive material are undergoing radioactive decay. The time gap between the instances when a quarter of the nuclei…MediumSingle correct
  3. 3 Sep 2020, Shift 1 · Q19In a radioactive material, fraction of active material remaining after time t is 9/16. The fraction that was remaining after t/2 is :EasySingle correct
  4. 2 Apr 2017 (offline) · Q26A radioactive nucleus A with a half life T, decays into a nucleus B. At t=0t=0, there is no nucleus B. At sometime t, the ratio of the…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.