Name the apparatus used for the measurement of the pressure of a gas.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the name of the apparatus used specifically for measuring the pressure of a gas.

2. **Identifying the Apparatus**: The primary instrument used for measuring gas pressure is called a "manometer."

3. **Types of Manometers**: There are different types of manometers, but one common type is the U-tube manometer. This consists of a U-shaped tube filled with liquid (often mercury or water) that measures pressure differences based on the height of the liquid columns.

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