Match List I with List II

Choose the correct answer from the options given below:

A-III, B-I, C-II, D-IV

The correct answer is Option (2) → A-III, B-I, C-II, D-IV.

Let’s analyze each reaction in detail and explain how the order of the reaction is determined.

A. $CH_3CHO\overset{773k}{\longrightarrow}CH_4+CO$: III. 1.5:

The reaction provided can be interpreted as:

\(CH_3CHO) \overset{773K}{\longrightarrow} CH_4 + CO\)

This is a thermal decomposition reaction where acetaldehyde decomposes upon heating to form methane and carbon monoxide.

As for the order of the reaction it may follow 1.5 order kinetics. This is somewhat unusual because reaction orders are commonly integer values (0, 1, 2, etc.), but fractional reaction orders are possible in certain complex mechanisms, often indicating that the rate law depends on more than one elementary step or involves intermediates.

B. $2NH_3\overset{Pt}{\longrightarrow}N_2+3H_2$: I. Zero order

This reaction represents the decomposition of ammonia on a platinum surface. In heterogeneous catalysis, especially when a gas reacts on a solid catalyst (like platinum in this case), zero-order kinetics often occur when the surface of the catalyst is fully covered by reactant molecules.

In such cases, increasing the concentration of ammonia will not affect the reaction rate because all the active sites on the catalyst are occupied, and the rate of reaction depends only on the efficiency of the catalyst and the temperature. Therefore, this reaction is also zero order with respect to ammonia.

C. $H_2+Br_2\longrightarrow 2HBr$ : II. Fractional order

This is the formation of hydrogen bromide from hydrogen and bromine.

This reaction proceeds through a chain mechanism, where radicals play a significant role. As a result, the overall order of the reaction turns out to be fractional.

Experimental studies have shown that the reaction has a fractional order with respect to \( \text{H}_2 \) and \( \text{Br}_2 \). This means that the reaction is not simply first or second order but has a fractional order due to the complex nature of the mechanism.

D. $SO_2Cl_2\longrightarrow SO_2+Cl_2$: IV. First order

This reaction is the decomposition of sulfuryl chloride (\( \text{SO}_2\text{Cl}_2 \)). It is a first-order reaction because the rate of reaction depends directly on the concentration of sulfuryl chloride. The reaction follows simple first-order kinetics, where the rate is proportional to the concentration of one reactant, in this case, \( \text{SO}_2\text{Cl}_2 \).

The correct matching is: 2. A-I, B-I, C-III, D-IV