A cylinder contains hydrogen gas at pressure 249 kPa and temperature 27$$^\circ $$C
Its density is : (R = 8.3 J mol^-1 K^-1)

The quantities of heat required to raise the temperature of two solid copper spheres of radii r₁ and r₂ (r₁ = 1.5r₂) through 1 K are in the ratio :

Two cylinders A and B of equal capacity are connected to each other via a stop cock. A contains an ideal gas at standard temperature and pressure. B is completely evacuated. The entire systems is thermally insulated. The stop cock is suddenly opened. The Process is :

In which of the following processes, heat is neither absorbed nor released by a system?