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Friday, 9 October

NEET UG 2017 · Physics · Question 3

NEET 2017 Physics, question 3

Question 3 of the NEET 2017 paper (code A) is a Physics question from Nuclei. Its idea, Radioactive Decay Law, was asked only this once in NEET 2017–2026. The CBSE official answer key gives option 2.

Updated 2026-10-08

Q3 · Physics

Radioactive material 'A' has decay constant '8 λ\lambda' and material 'B' has decay constant 'λ\lambda'. Initially they have same number of nuclei. After what time, the ratio of number of nuclei of material 'B' to that 'A' will be 1e\frac{1}{e} ?

  1. 11λ\frac{1}{\lambda}
  2. 217λ\frac{1}{7\lambda}Official answer
  3. 318λ\frac{1}{8\lambda}
  4. 419λ\frac{1}{9\lambda}

Official answer: option 2 · CBSE official answer key

Same idea

The only question on Radioactive Decay Law

No other NEET paper from 2017–2026 tested this exact idea.

Radioactive Decay Law: every question and how it was framed

The chapter

Nuclei in ten years of NEET

13 questions from 2017–2026, asked in 9 of 10 papers, about 1.2 a paper. Radioactive Decay alone had 9.

Chapter analysisStudy this chapterPractise this chapter

Nuclei: questions per paper

0241’171’181’192’203’212’221’231’240’251’26