A barometer tube is 1 m long and `2cm^(2)` in cross section. Mercury stands to a height of `75cm` in the tube. When a small amount of oxygen is introduced in the space above the mercury level, the level falls by 5cm. Calculate the mass of the oxygen is introduced. Room temperature=`27^(@)C`, g=10 m s_(-2)` and density if mercury =`13600kg m^(-3)`.

Explanation

To solve the problem step by step, we will follow the given information and apply the relevant physics concepts.

### Step 1: Identify the Given Data
- Length of the barometer tube, \( L = 1 \, \text{m} \)
- Cross-sectional area of the tube, \( A = 2 \, \text{cm}^2 = 2 \times 10^{-4} \, \text{m}^2 \)
- Initial height of mercury, \( h_1 = 75 \, \text{cm} = 0.75 \, \text{m} \)
- Fall in mercury level, \( \Delta h = 5 \, \text{cm} = 0.05 \, \text{m} \)
- Final height of mercury, \( h_2 = h_1 - \Delta h = 0.75 \, \text{m} - 0.05 \, \text{m} = 0.70 \, \text{m} \)
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