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Time for a reactant to fall to a quarter of its amount from the half-life

The same question, asked 2 times: 3 May 2023 S1*, 19 Apr 2026 S2. Every wording below, oldest first.

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  1. Question 1

    3 May 2023 S1

    66
    What time is required for 100 g of reactant to reduce to 25 g in a first order reaction having half-life 5760 year?

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  2. Question 2

    19 Apr 2026 S2

    33
    For a first order reaction, half life is 55 hour. What time is required to reduce 1010 g of reactant to 2.52.5 g ?

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