Which of the words-out of reversible, irreversible, adiabatic, isothermal, isochoric and isobaric-will you choose to describe the following processes–
(i) A bullet stops in a target [system is bullet plus target].
(ii) A gas, enclosed in a metallic cylinder provided with a piston, is slowly expanded [System is gas]. There is friction between piston and cylinder.
(iii) A piece of hot stone (which has coefficient of thermal expansion equal to zero) is dipped into cold water [System is stone].

Answer

(i) irreversible adiabatic (ii) isothermal (iii) irreversible isochoric