Match List-I with List-II
| List-I | List-II |
| Specific terms | Observations |
| (A) Instantaneous rate | (I) rate at a particular moment of time |
| (B) Rate law | (II) sum of powers of the concentration of the reactants in the rate law expression |
| (C) Order of a reaction | (III) representation of rate of reaction in terms of concentration of the reactants |
| (D) Elementary reaction | (IV) reactions taking place in one step |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A) - (I), (B) - (III), (C) - (II), (D) - (IV)
These are the basic terms of chemical kinetics. For a reaction aA + bB → products, the experimentally found rate law is written as:
\( \displaystyle \text{Rate}=k[\text{A}]^{x}[\text{B}]^{y} \)
(A) Instantaneous rate — This matches (I) rate at a particular moment of time. It is the slope of the tangent to the concentration-time curve at that instant.
\( \displaystyle r_{\text{inst}}=-\frac{d[\text{R}]}{dt} \)
(B) Rate law — This matches (III) representation of rate of reaction in terms of concentration of the reactants. The rate law above expresses the rate in terms of the concentrations of the reactants, each raised to some power.
(C) Order of a reaction — This matches (II) sum of powers of the concentration of the reactants in the rate law expression. For the rate law above, order = x + y.
(D) Elementary reaction — This matches (IV) reactions taking place in one step. An elementary reaction occurs in a single step; a complex reaction is a sequence of such steps.
Shortcut: The pair (B)–(III) appears only in Option (1).