Name the method used for obtaining ammonia on a large scale .

Explanation

**Step-by-Step Solution:**

1. **Identify the Process**: The method used for obtaining ammonia on a large scale is known as the Haber process.

2. **Chemical Reaction**: The Haber process involves the reaction of nitrogen gas (N₂) and hydrogen gas (H₂) to produce ammonia (NH₃). The balanced chemical equation for this reaction is:
\[ N_2(g) + 3H_2(g) \rightarrow 2NH_3(g) \]
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