The contact process is used for the industrial production of

1. Analyze the question

The question asks for the specific industrial process known as the "Contact process" and which chemical substance it is used to manufacture.

2. Explain the concept

In industrial chemistry, different processes are used to produce common chemicals on a large scale.

• The Contact Process: This is the standard industrial method for producing sulfuric acid ($H_2SO_4$). It involves the catalytic oxidation of sulfur dioxide ($SO_2$) to sulfur trioxide ($SO_3$), which is then absorbed in concentrated sulfuric acid to form oleum, followed by dilution with water.
• Other processes for context: • Haber Process: Used for the production of Ammonia ($NH_3$). • Solvay Process: Used for the production of Sodium carbonate ($Na_2CO_3$). • Downs Process: Used for the production of Sodium metal.

3. Show the solution

• Step 1: Identify the key stages of the Contact Process: • Burning sulfur in air to produce sulfur dioxide: $S(s) + O_2(g) \rightarrow SO_2(g)$ • Catalytic oxidation of sulfur dioxide: $2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)$ (using Vanadium(V) oxide as a catalyst). • Absorption of $SO_3$ in concentrated $H_2SO_4$ to form oleum ($H_2S_2O_7$). • Dilution of oleum to produce concentrated sulfuric acid.
• Step 2: Compare this with the options provided. The process clearly leads to the production of sulfuric acid.

4. Identify the answer

The correct option is A.

5. Exam Tip

To avoid confusion in the exam hall, remember this mnemonic: "Contact for Acid, Haber for Ammonia." Also, always remember that the catalyst used in the Contact process is Vanadium(V) oxide ($V_2O_5$)—JAMB loves to ask about that catalyst!