In a first order reaction, the concentration of the reactant decreases from 0.8\ M to 0.4\ M in 15 minutes. The time taken for the concentration to ch - Chemistry MCQ AIEEE 2004 2026 | ExamTest.live | ExamTest.live

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In a first order reaction, the concentration of the reactant decreases from 0.8 M to 0.4 M in 15 minutes. The time taken for the concentration to change from 0.1 M to 0.025 M is:

A $30 minutes$
B $60 minutes$
C $7.5 minutes$
D $15 minutes$

Solution & Step-by-step Explanation

* In a first-order reaction, the half-life (t_{1/2}) is constant.Decrease from 0.8 M to 0.4 M is one half-life. Thus, t_{1/2} = 15 minutes.To change from 0.1 M to 0.025 M : 0.1 M \to 0.05 M (1st half-life) 0.05 M \to 0.025 M (2nd half-life)Total time = 2 \times t_{1/2} = 2 \times 15 = 30 minutes.

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In a first order reaction, the concentration of the reactant decreases from 0.8 M to 0.4 M in 15 minutes. The time taken for the concentration to change from 0.1 M to 0.025 M is:

A

30 minutes

B

60 minutes

C

7.5 minutes

D

15 minutes

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chemical kinetics first order reaction

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