Two vessels A and B are of the same size and are at same temperature. A contains 1 g of hydrogen and B contains 1 g of oxygen. P_A and P_B are the pressures of the gases in A and B respectively, then P_A/P_B is:

Solution

Physics sir · 3 steps

Same volume, same temperature: pressure just follows the number of moles, so count moles.

1. Pressure tracks moles. From PV = nRT, with V and T the same for both vessels, P ∝ n. So the pressure ratio equals the mole ratio.
2. Count moles. Hydrogen is diatomic, H₂, with molar mass 2 g mol⁻¹, so n_A = 1/2 mol. Oxygen is O₂, with molar mass 32 g mol⁻¹, so n_B = 1/32 mol.

   P_A/P_B = n_A/n_B = (1/2)/(1/32) = 16

3. So. P_A/P_B = 16, which is option (d).

The idea to keep. When two gases share the same V and T, compare pressures by comparing moles. Equal masses give moles in the inverse ratio of molar masses, and gases like H₂ and O₂ are diatomic.

Answer from the NTA final answer key. Solution by PrepWiser.