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Time for one extent of a first order reaction from the time taken for another

This type of question, asked 7 times: 2 May 2023 S2, 4 May 2023 S2, 10 May 2024 S2, 11 Apr 2026 S1, 15 Apr 2026 S1, 17 Apr 2026 S1, 15 May 2026 S1. All 7 questions below, oldest first.

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  1. Question 1

    2 May 2023 S2

    96
    In a first order reaction, the concentration of reactant drops from 0.8 mol L−10.8\,\text{mol L}^{-1} to 0.4 mol L−10.4\,\text{mol L}^{-1} in 15 minutes. What is the time required to drop from 0.1 mol L−10.1\,\text{mol L}^{-1} to 0.025 mol L−10.025\,\text{mol L}^{-1}?

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  2. Question 2

    4 May 2023 S2

    75
    What is the half-life of a first order reaction if time required to decrease concentration of reactant from 0.8 M to 0.2 M is 12 hour?

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  3. Question 3

    10 May 2024 S2

    70
    Time required for 90% completion of a first order reaction is 'xx' minute. Calculate the time required to complete 99.9% of the reaction at same temperature.

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  4. Question 4

    11 Apr 2026 S1

    27
    A first order reaction complete 60%60\% in 2020 minutes. How long will the reaction take to complete 84%84\%?

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  5. Question 5

    15 Apr 2026 S1

    27
    The time required for 90%90\% completion of a certain first order reaction is 11 hour. Calculate the time required for 99.9%99.9\% completion of the same reaction.

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  6. Question 6

    17 Apr 2026 S1

    29
    If time required for 90 % completion of a first order reaction is 'tt'. What is the time required for 99.9 % completion of reaction at same temperature?

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  7. Question 7

    15 May 2026 S1

    27
    If time required for 99%99\% completion of a first order reaction is tt minutes, find the time required for 99.9%99.9\% completion.

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