3 kg of oxygen undergoes a non-flow process during which its pressure remains constant at 7 bar from an initial volume of 1200 litres to a state where the temperature is \(520 \mathrm{~K}\). Find \((a)\) changes in internal energy, \((b)\) change in enthalpy, \((c)\) heat transferred, and \((d)\) work done.

For oxygen, \(c_{v}=0.661 \mathrm{~kJ} / \mathrm{kg} . K, c_{p}=0.921 \mathrm{~kJ} / \mathrm{kg}\). K.