Rate constant ‘k’ for a certain reaction is k = 2.3 × 10−5 L mol−1 s−1. Order of the reaction is:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 2
The unit of the rate constant depends on the order of the reaction. For an nth order reaction:
\( \displaystyle k = \frac{\text{rate}}{[\text{A}]^n} = \frac{\text{mol L}^{-1}\,\text{s}^{-1}}{(\text{mol L}^{-1})^n} = (\text{mol L}^{-1})^{1-n}\,\text{s}^{-1} \)
The given unit is L mol−1 s−1 = (mol L−1)−1 s−1, so
\( 1 - n = -1 \;\Rightarrow\; n = 2 \)
The reaction is of the second order.
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 – …
