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 :

Each side of a box made of metal sheet in cubic shape is 'a' at room temperature 'T', the coefficient of linear expansion of the metal sheet is '$$\alpha$$'. The metal sheet is heated uniformly, by a small temperature $$\Delta$$T, so that its new temperature is T + $$\Delta$$T. Calculate the increase in the volume of the metal box.

In a dilute gas at pressure P and temperature T, the mean time between successive collisions of a molecule varies with T as :

Three rods of identical cross-section and lengths are made of three different materials of thermal conductivity K₁ , K₂ and K₃ , respecrtively. They are joined together at their ends to make a long rod (see figure). One end of the long rod is maintained at 100^oC and the other at 0^oC (see figure). If the joints of the rod are at 70^oC and 20^oC in steady state and there is no loss of energy from the surface of the rod, the correct relationship between K₁ , K₂ and K₃ is :