Identify the gas evolved in each of the cases:
A colourless gas liberated on decomposition of nitric acid.

Explanation

To identify the gas evolved during the decomposition of nitric acid, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Decomposition of Nitric Acid**:
- Nitric acid (HNO3) can decompose when heated or exposed to sunlight.

2. **Write the Decomposition Reaction**:
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