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  9. Q50

MPSC State Service 2020 · GS · Question 50 of 97

Tritium has a half-life of 12.5 years, undergoing beta decay. What fraction of original Tritium will remain undecayed after 25 years?

Physics

  1. A0 (zero)
  2. B0.5
  3. C0.25Correct
  4. D0.125

Answer: C. 0.25

Explanation

After 25 years (two half-lives of 12.5 years), the undecayed fraction is (1/2)^2 = 0.25.

Source: MPSC Rajyaseva Prelims 2020 – GS Paper I (Set D), official paper

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