NEET2020Chemistry-Chemical Kinetics
NEET 2020 Chemistry First Order Reactions MCQ Question
Type: MCQ-numerical-Easy-Class 12
The rate constant for a first order reaction is 4.606 × 10⁻³ s⁻¹. The time required to reduce 2.0 g of the reactant to 0.2 g is:
A
500 s
B
1000 s
C
100 s
D
200 s
Correct Answer
Option A
Detailed Explanation
For a first order reaction, t = (2.303/k) × log(initial/final) = (2.303/4.606 × 10⁻³) × log(2.0/0.2) = 500 × log(10) = 500 × 1 = 500 s. The correct answer is A (500 s). The original explanation incorrectly calculated 1000 s.
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