Why the process of manufacture of `H_2SO_4` is named contact process ?

Explanation

### Step-by-Step Solution:

1. **Understanding the Process**: The manufacture of sulfuric acid (H₂SO₄) involves several steps, one of which is the conversion of sulfur or sulfide ores into sulfur dioxide (SO₂) by burning them in air.

2. **Chemical Reaction**: The main reaction in the contact process starts with the combustion of sulfur or sulfide ores. For example, iron pyrite (FeS₂) reacts with oxygen (O₂) to produce iron(III) oxide (Fe₂O₃) and sulfur dioxide (SO₂). The balanced equation for this reaction is:
\[ 4 \text{FeS}_2 + 11 \text{O}_2 \rightarrow 2 \text{Fe}_2\text{O}_3 + 8 \text{SO}_2 \]
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