Question

A reaction of first order takes 10 minutes to achieve 50% conversion. The conversion achieved after 20 minutes is ____

(a) 0.5

(b) 0.75

(c) 0.87

(d) 0.9

This question was addressed to me in a national level competition.

I'm obligated to ask this question of Conversion and Reactor Sizing in section Ideal Reactors for a Single Reaction, Conversion and Reactor Sizing of Chemical Reaction Engineering

Answer 1

The correct answer is (b) 0.75

The explanation is: -ln(1-XA) = kt

XA = 0.75.