A manometer reads the pressure of a gas in an enclosure as shown in the figure. The absolute and gauge pressure of the gas in cm of mercury is (take atmospheric pressure =76 cm of mercury)

Options

A. 76,20
B. 20,76
C. 96,20
D. 20,96

Explanation

To solve the problem regarding the pressure of a gas in an enclosure as measured by a manometer, we will follow these steps:

### Step-by-Step Solution:

1. **Identify Given Values**:
- Atmospheric pressure (P₀) = 76 cm of mercury
- Height of the pressure head (H) = 20 cm of mercury

2. **Calculate Absolute Pressure**:
- The formula for absolute pressure (P) is given by:
\[ P = P₀ + H \]
- Substitute the known values into the formula:
\[ P = 76 \, \text{cm of mercury} + 20 \, \text{cm of mercury} \]
- Perform the addition:
\[ P = 96 \, \text{cm of mercury} \]

3. **Calculate Gauge Pressure**:
- The gauge pressure (P_g) is defined as the difference between the absolute pressure and the atmospheric pressure:
\[ P_g = P - P₀ \]
- Substitute the values:
\[ P_g = 96 \, \text{cm of mercury} - 76 \, \text{cm of mercury} \]
- Perform the subtraction:
\[ P_g = 20 \, \text{cm of mercury} \]

4. **Final Results**:
- Absolute Pressure = 96 cm of mercury
- Gauge Pressure = 20 cm of mercury

### Summary of Results:
- Absolute Pressure: 96 cm of mercury
- Gauge Pressure: 20 cm of mercury