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STANDARD Chemistry First Order Reactions MCQ Question

Type: MCQ-numerical-Medium-Class 12

A first order reaction has a rate constant 1.15 × 10⁻³ s⁻¹. How long will 5g of this reactant take reduce to 3g?

A

444 s

B

400 s

C

528 s

D

669 s

Correct Answer

Option A

Detailed Explanation

For a first order reaction, the time t can be calculated using the formula t = 2.303/k log(R₀/R), where R₀ is the initial amount and R is the remaining amount. Substituting R₀ = 5g, R = 3g, and k = 1.15 × 10⁻³ s⁻¹, t = 444 s.

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