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JEE Main 2025 Jan 29 Shift 2, Chemistry Q17: Reactions of Various Orders

JEE Main2025Jan 29, Shift 2Chemistry
Q.

Drug X becomes ineffective after 50% decomposition. The original concentration of drug in a bottle was 16 mg/mL which becomes 4 mg/mL in 12 months. The expiry time of the drug in months is _____.

Assume that the decomposition of the drug follows first order kinetics.

  1. A

    12

  2. B

    2

  3. C

    3

  4. D

    6

Solution

For first-order kinetics, the half-life is independent of initial concentration.

From mg/mL the concentration falls by a factor of , i.e. two successive half-lives have elapsed in months.

months.

The drug becomes ineffective at decomposition, which is exactly one half-life.

Expiry time months.

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