Vital capacity of a normal adult person is about................ to ..................... litres.

Explanation

**Step-by-Step Solution:**

1. **Understand the Concept of Vital Capacity**: Vital capacity refers to the maximum amount of air a person can exhale after taking the deepest possible breath. It is an important measure of lung function.

2. **Identify the Normal Range**: For a normal adult person, the vital capacity typically ranges from 3 to 5 litres. This range can vary based on factors such as age, gender, body composition, and physical fitness.

3. **State the Answer**: Therefore, the vital capacity of a normal adult person is about 3 to 5 litres.

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