Question

In a first order reaction, the time required for the completion of 99% is _______ for its 90% completion.

(a) Same

(b) Negligible

(c) Thrice

(d) Twice

This question was posed to me by my college professor while I was bunking the class.

My doubt is from Integrated Rate Equation and Half Lives topic in chapter Reaction Dynamics of Engineering Chemistry I

Answer 1

Correct choice is (d) Twice

To elaborate: In a first order reaction, the time required for the completion of 99% is twice for its 90% completion. ln [A] = -kt + ln [A0].