State Gay-Lusaac’s law 

Explanation

### Step-by-Step Solution:

1. **Definition of Gay-Lussac's Law**:
Gay-Lussac's Law states that the pressure exerted by a gas of a given mass, when kept at a constant volume, varies directly with the absolute temperature of the gas.

2. **Understanding the Relationship**:
- When the volume (V) and the amount of gas (n) are held constant, the ideal gas equation \(PV = nRT\) simplifies to show that pressure (P) is directly proportional to temperature (T).
- This can be expressed mathematically as:
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