Take timed practice tests on States of Matter and Gaseous State for JEE Main and JEE Advanced with session-wise drills, score review, and explanation-led revision.
Six 20-question timed sessions plus a 60-question chapter module. Each item is original and reframed for copyright safety.
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1. The ideal gas equation is:
Explanation: Ideal gas law: PV = nRT, where P = pressure, V = volume, n = moles, R = 8.314 J mol⁻¹ K⁻¹, T = temperature in K. Assumes no intermolecular forces and point-mass particles.
2. Boyle's law states that at constant T and n:
Explanation: Boyle's Law: at constant temperature and amount, P₁V₁ = P₂V₂. Pressure and volume are inversely proportional: P ∝ 1/V.
3. Charles' law states that at constant P:
Explanation: Charles' Law: at constant pressure and amount, V/T = constant → V₁/T₁ = V₂/T₂. Volume is proportional to absolute temperature (T in Kelvin).
4. The van der Waals equation (P + a/V²)(V − b) = RT accounts for:
Explanation: van der Waals corrections: (1) 'a' corrects for intermolecular attractions — actual pressure is less than ideal (molecules slow down near walls). (2) 'b' corrects for finite volume of molecules — actual free volume is less than V.
5. The root mean square speed (urms) of gas molecules is:
Explanation: urms = √(3RT/M) where M = molar mass in kg/mol. Also: average speed u_avg = √(8RT/πM), most probable speed ump = √(2RT/M). Ratio: urms : u_avg : ump = √3 : √(8/π) : √2.
6. Graham's law of effusion states that the rate of effusion is:
Explanation: Graham's law: r₁/r₂ = √(M₂/M₁). Lighter gases effuse faster. Used to separate isotopes (UF₆) and determine molar masses from effusion rates.
7. Above the critical temperature (Tc), a gas:
Explanation: Above Tc, the distinction between gas and liquid disappears. No amount of pressure can liquefy the gas above Tc. Below Tc, sufficient pressure can liquefy a gas (vapour).
8. At STP (0°C, 1 atm), 1 mole of an ideal gas occupies:
Explanation: Molar volume of ideal gas at STP (0°C = 273 K, 1 atm): V = nRT/P = (1)(0.0821)(273)/1 = 22.4 L. At SATP (25°C, 1 bar), molar volume ≈ 24.8 L.
9. For an ideal gas, the compressibility factor Z (= PV/nRT) is:
Explanation: Z = PV/nRT = 1 for ideal gas (by definition). For real gases: Z 1 at very high pressures (repulsive forces dominate, b term dominates).
10. The mean free path (λ) of gas molecules is:
Explanation: Mean free path λ = 1/(√2 π d² n) where d = molecular diameter and n = number density. λ decreases with increasing pressure and decreasing temperature. Viscosity, thermal conductivity, and diffusion are related to mean free path.
11. At constant volume, doubling the absolute temperature of a gas:
Explanation: Gay-Lussac's Law: P/T = constant at constant V and n. Doubling T doubles P: P₂ = P₁ × T₂/T₁ = P₁ × 2.
12. The liquefaction of gases is achieved by:
Explanation: To liquefy a gas: (1) temperature must be below Tc (critical temperature), (2) pressure must exceed the vapour pressure at that temperature. The Linde process (Joule-Thomson expansion) and compression-cooling are used industrially.
13. For a mixture of gases, Dalton's law of partial pressures states:
Explanation: Dalton's Law: total pressure of a non-reacting gas mixture = sum of partial pressures. Pᵢ = xᵢ × P_total, where xᵢ = mole fraction of component i.