`O_(2)` is collected over water at `20^(@) C` . The pressure inside shown by the gas is 740 mm of Hg . What is the pressure due to `O_2` along if vapour pressure of `H_2 O` is 18 mm at `20^(@) C` ?

Options

A. 740 mm
B. 370 mm
C. 722 mm
D. 758 mm

Explanation

To find the pressure due to \( O_2 \) alone when it is collected over water, we can use the following steps:

### Step-by-Step Solution:

1. **Understand the Given Data**:
- The total pressure of the gas collected (moist gas) is given as \( 740 \, \text{mm Hg} \).
- The vapor pressure of water at \( 20^\circ C \) is given as \( 18 \, \text{mm Hg} \).

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