21) According to Gay-Lussac law for a perfect gas, p/T = constant, if v is kept constant.

22) There is no change in internal energy in an isothermal process.

23) If the value of n = 0 in the equation pvn = C, then the process is called

24) The value of specific heat at constant pressure (cp) is __________ that of at constant volume (cv).

25) When coal is strongly heated continuously for 42 to 48 hours in the absence of air in a closed vessel, the process is known as __________ of fuel.