Question

The rate constant of the reaction $A\to B$ is $0.6\times {10}^{-3}{\text{mol L}}^{-1}{\text{s}}^{-1}$. If the concentration of $A$ is $5M$, then concentration of $B$ after $20$ minutes is:

• A. $3.60M$
• B. $0.36M$
• C. $0.72M$
• D. $1.08M$

Answer 1

The correct option is C $0.72M$

Reaction is of zero order as the unit of rate constant is ${\text{mol L}}^{-1}{\text{s}}^{-1}$.
Concentration of $B=k\times t$
$=0.6\times {10}^{-3}\times 20\times 60=0.72M$