What will be the order of a reaction if its rate is expressed as
Rate = \( k[A]^{1/2}[B]^{3/2} \)
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 2
The order of a reaction is the sum of the powers of the concentration terms in the rate law. For Rate \( = k[\mathrm{A}]^{x}[\mathrm{B}]^{y} \), the order is \( x + y \). The powers are found by experiment and need not be whole numbers.
\( \displaystyle \text{Rate} = k[\mathrm{A}]^{1/2}[\mathrm{B}]^{3/2} \)
\( \displaystyle \text{order} = \frac{1}{2} + \frac{3}{2} = 2 \)
So the reaction is of order 2 (second order), although neither reactant has a whole-number power.
Note: This question is from NCERT (2026-27). NTA sets numerical questions from NCERT too, so do not ignore NCERT while practising numericals.
NCERT (2026-27 edition):
Order of a Reaction – …
