Question

If the rate of reaction $A\to B$ doubles on increasing the concentration of A by 4 times, then the order of reaction is :

• A. 2
• B. 1
• C. $\frac{1}{2}$
• D. 4

Answer 1

The correct option is C $\frac{1}{2}$

Let the rate of the reaction be $r=K[A{]}^n$ .........(1)
When $\left[A\right]\to 4\left[A\right]$, rate will be $r\to 2r$
$2r=4^n[A{]}^n$ ..........(2)
By comparing equations (2) and (1), $2=4^n$
This is only possible when $n=\frac{1}{2}$.