If the concentration of a reactant is reduced to half, the rate of reaction becomes 1/4. What will be the order of reaction?

2

The correct answer is Option (3) → 2

Rate law:

$\text{Rate} \propto [A]^n$

When concentration is reduced to half:

$\left(\frac{1}{2}\right)^n = \frac{1}{4}$

$\left(\frac{1}{2}\right)^n = \left(\frac{1}{2}\right)^2$

So,

$n = 2$