What is the pressure of air in the air columns, when the tube was horizontal? — States of Matter and Gaseous State Chemistry Question

💡 Solution & Explanation

Horizontal: $P_{AB} = P_{CD} = P_0$. Vertical A up: AB expands to 30 cm, CD compresses to 50 cm. $P'_{AB} = P_0(20/30) = 2P_0/3$. $P'_{CD} = P_0(60/50) = 6P_0/5$. Gravity balance: $P'_{CD} = P'_{AB} + 20 \implies 6P_0/5 = 2P_0/3 + 20 \implies 8P_0/15 = 20 \implies P_0 = 37.5 \text{ cm Hg}$. Therefore, correct answer is B.