Assertion: `50%` of reaction is completed in `50 sec`, therefore, `75%` of the reaction will be completed in `75 sec`.
Reason: The rate constant of a zero order reaction depends uopn time as `k = (1)/(t){[A]_(0) - [A]}`.

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but the reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If assertion is false but reason is true.

Answer

C

Explanation

Correct Reason Rate constant of any reaction is constant at constant temperature and does not change with time or concentration. However, Assertion is correct because
`t = (1)/(k){[A]_(0) - [A]}`
For `50%`, `t_(50%) = (1)/(k){[A]_(0) - ([A]_(0))/(2)} = ([A]_(0))/(2k) = 50 sec`
For `75%`, `t_(75%) = (1)/(k){[A]_(0) - ([A]_(0))/(4)}`
`= ([A]_(0))/(k) xx (3)/(4) = ([A]_(0))/(2k) xx (3)/(2) = 75 sec`