Match List-I with List-II
| List-I | List-II |
| Concepts in chemical kinetics | Detail |
| (A) Order applies | (I) Zero order reaction |
| (B) Molecularity applies | (II) First order reaction |
| (C) 2NH3(g) → N2(g) + 3H2(g) (1130 K, Pt Catalyst) | (III) To elementary as well as complex reactions |
| (D) \( \mathrm{{}^{226}_{88}Ra\rightarrow {}^{4}_{2}He+{}^{222}_{86}Rn} \) | (IV) Only for elementary reactions. |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A) - (III), (B) - (IV), (C) - (I), (D) - (II)
Order is the sum of the powers of the concentration terms in the experimental rate law. Molecularity is the number of reacting species that collide at the same time in a single step. Each item is matched as follows:
(A) Order applies — This matches (III) To elementary as well as complex reactions. Order is found by experiment for any reaction. For a complex reaction it is decided by the slowest step.
(B) Molecularity applies — This matches (IV) Only for elementary reactions. Molecularity describes a single collision step, so it has no meaning for a complex reaction as a whole.
(C) 2NH3(g) → N2(g) + 3H2(g) (1130 K, Pt Catalyst) — This matches (I) Zero order reaction. At high pressure the platinum surface is completely covered with ammonia, so a change in the concentration of ammonia does not change the rate.
\( \displaystyle \text{Rate}=k[\ce{NH3}]^0=k \)
(D) \( \mathrm{{}^{226}_{88}Ra\rightarrow {}^{4}_{2}He+{}^{222}_{86}Rn} \) — This matches (II) First order reaction. All natural radioactive decay follows first order kinetics: the rate depends only on the number of undecayed nuclei.
\( \displaystyle \text{Rate}=k[\ce{Ra}] \)
Shortcut: The pair (C)–(I) appears in Options (1) and (3), and (A)–(III) then leaves only Option (1).