If one mole of an ideal gas at (P₁, V₁) is allowed to expand reversibly and isothermally (A to B) its pressure is reduced to one-half of the original pressure (see figure). This is followed by a constant volume cooling till its pressure is reduced to one-fourth of the initial value (B $$ \to $$ C). Then it is restored to its initial state by a reversible adiabatic compression (C to A). The net workdone by the gas is equal to :

On the basis of kinetic theory of gases, the gas exerts pressure because its molecules :

Match List I with List II.

	List I		List II
(a)	Isothermal	(i)	Pressure constant
(b)	Isochoric	(ii)	Temperature constant
(c)	Adiabatic	(iii)	Volume constant
(d)	Isobaric	(iv)	Heat content is constant

Choose the correct answer from the options given below :

n mole of a perfect gas undergoes a cyclic process ABCA (see figure) consisting of the following processes.

A $$ \to $$ B : Isothermal expansion at temperature T so that the volume is doubled from V₁ to V₂ = 2V₁ and pressure charges from P₁ to P₂

B $$ \to $$ C : Isobaric compression at pressure P₂ to initial volume V₁.

C $$ \to $$ A : Isochoric change leading to change of pressure from P₂ to P₁.

Total workdone in the complete cycle ABCA is :