Question

Assertion: Work done by a gas in isothermal expansion is more than the work done by the gas in the same expansion, adiabatically. Reason: Temperature remains constant in isothermal expansion and not in adiabatic expansion

Assertion (A): Real gases obey the ideal gas law at all temperatures and pressures. Reason (R): Real gases behave like ideal gases only at high temperatures and low pressures.

Properties of gases are easier to understand than those of solids and liquids. This is mainly because in a gas, molecules are far from each other and their mutual interactions are negligible except when two molecules collide. The perfect gas equation can be written as PV = µRT where µ is the number of moles and R = NA kB is a universal constant. The temperature T is absolute temperature. Choosing kelvin scale for absolute temperature, R = 8.314 J mol-1K-1. If we fix µ and T in the equation, we get PV = constant i.e., keeping temperature constant, pressure of a given mass of gas varies inversely with volume. This is the famous Boyle's law. Next, if you fix P, shows that V ∝ T i.e., for a fixed pressure, the volume of a gas is proportional to its absolute temperature T (Charles' law).

The isothermal diagram of a gas at three different temperatures T₁, T₂ and T₃, is shown in the given figure. Then