Match List I with List II

A-4; B-2; C-3; D-1

The correct answer is option (4) 4. A-4; B-2; C-3; D-1

Let us go through each substance (List I) and its corresponding process (List II) in detail:

A. Sulphuric Acid : 4. Contact Process

The Contact Process is used to produce sulfuric acid \((H_2SO_4)\) from sulfur dioxide \((SO_2)\) and oxygen \((O_2)\). In this process, sulfur dioxide is oxidized to sulfur trioxide \((SO_3)\) in the presence of a vanadium \((V)\) oxide \((V_2O_5)\) catalyst. The overall reaction can be represented as follows:
\(2 \text{SO}_2(g) + \text{O}_2(g) \overset{\text{V}_2\text{O}_5}{\longrightarrow} 2 \text{SO}_3(g)\)
The sulfur trioxide produced is then dissolved in water to form sulfuric acid.

B. Steel: 2. Bessemer's Process

Bessemer's Process is a method for producing steel by blowing air through molten pig iron to oxidize impurities and adjust the carbon content. The oxidation of impurities helps in the removal of excess carbon, silicon, and manganese, resulting in the production of steel with the desired composition. The reaction involves the following steps:

\(\text{Fe} + \text{C} \rightarrow \text{FeC}\)

\(\text{Fe} + \text{Si} \rightarrow \text{FeSi}\)

\(\text{Fe} + \text{Mn} \rightarrow \text{FeMn}\)

The impurities are then removed as slag.

C. Sodium Hydroxide: 3. Leblanc Process

The Leblanc Process is a historical method for producing sodium carbonate (soda ash) from sodium chloride (table salt). The process involves several steps:
     1. Sodium chloride is reacted with sulfuric acid to produce sodium sulfate and hydrochloric acid.
     \[\text{NaCl} + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + 2\text{HCl}\]
     2. Sodium sulfate is then heated with limestone (calcium carbonate) and coal to produce sodium carbonate and calcium sulfide.
     \[\text{Na}_2\text{SO}_4 + \text{CaCO}_3 + 2\text{C} \rightarrow 2\text{Na}_2\text{CO}_3 + \text{CaS} + 2\text{CO}_2\]
     3. The sodium carbonate is then extracted from the mixture.

D. Ammonia:1. Haber's Process

Haber's Process is used to synthesize ammonia \((NH_3)\) from nitrogen \((N_2)\) and hydrogen \((H_2)\) under high pressure and temperature, in the presence of an iron catalyst. The balanced equation for the reaction is:
\[N_2(g) + 3H_2(g) \overset{\text{Fe}}{\longrightarrow} 2NH_3(g)\]
This process is crucial for the production of ammonia, which is a key component in fertilizers and various other industrial applications.

So, the correct matching is 4. A-4; B-2; C-3; D-1.