A uniform tube closed at aone end, contains a pellet of mercury 10cm long. When the tube is lept vertically with the closed-end upward, the length of the air column trapped is 20cm. Find the length of the air column trapped when the tube is inverted so that the closed-end goes down. Atmospheric pressure`=75cm of mercury.

Explanation

To solve the problem step by step, we will analyze the situation and apply the principles of physics, particularly Boyle's Law, which states that for a given mass of gas at constant temperature, the product of pressure and volume is a constant.

### Step-by-Step Solution:

1. **Understand the Initial Conditions**:
- The tube is closed at one end and contains a 10 cm long pellet of mercury.
- When the tube is vertical with the closed end up, the length of the air column trapped is 20 cm.

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