Practice question

**Ideal gas internal energy** proportional to temperature, U = (f/2) R T per mole, monatomic 3/2 R T, diatomic 5/2 R T, change ΔU = f/2 n R ΔT, for temperature increase internal energy rises, explaining why heating gas at constant volume raises U entirely as heat. Boyle’s law: P₁ V₁ = P₂ V₂.P₁ = 2.5 atm, V₁ = 12 litres, P₂ = 5 atm.V₂ = (P₁ V₁)/(P₂) = (2.5 × 12)/(5) = 6 litres. Substituting values gives 6 litres, which matches expected kinetic theory result, confirming mean free path λ = 1/(√2 n π d²), ideal gas law P V = n R T