One of the limbs of a mercury manometer is connected to a gas cylinder. The mercury level in the limb connected to the gas cylinder is 10 cm higher than that in the other limb. Then the gauge pressure of the gas is _______ cm of Hg.

Explanation

To solve the problem of determining the gauge pressure of the gas in the gas cylinder connected to a mercury manometer, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Setup**: A mercury manometer has two limbs. One limb is connected to a gas cylinder, and the other is open to the atmosphere. The mercury level in the limb connected to the gas is 10 cm higher than in the other limb.

2. **Identify the Pressure Points**:
- Let’s denote the pressure at the point in the gas cylinder (connected to the manometer) as \( P_A \).
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