Question

A certain substance A is mixed with an equimolar quantity of substance B. At the end of an hour, A is 75% reacted. Calculate the time when A is 10% unreacted. (Given: order of reaction is zero)

• A. 1.2 hr
• B. 1.8 hr
• C. 2.0 hr
• D. 2.4 hr

Answer 1

The correct option is A 1.2 hr

According to zero order reaction:
$x=kt$ ( x = amount of reactant reacted)

$75=k\times 1$ and
$90=k\times t$
So $t=90/75=1.2$ hr