Among the following processes identify those in which the change in internal energy `(DeltaU)` is zero: (i) isothermal compression of an ideal gas (ii) adiabatic expansion of an ideal gas (iii) Free adiabatic expansion of an ideal gas (iv) reversible cyclic process (v) irreversible cyclic process.

Explanation

(i) The change in internal energy of an ideal gas in its isothermal compression is zero. (ii) when an ideal gas undergoes an adiabatic expansion, its internal energy decreases. (iii) in adiabatic free expansion of an ideal gas, the internal energy of the gas remains the same. (iv) and (v) since U is a state function, its change in any cyclic process (reversible or irreversible) will e zero.