heat transfer

A quantity of air has a mass of 0.05 kg and the pressure and temperature are 100 kPa and 310 K respectively. Stirring work is done on the gas by an impeller on a shaft passing through the system boundary. The torque on the shaft is 20 Nm. The shaft rotates at 500 rev/min for 35 seconds. The volume of the gas does not change and a heat transfer of 25 kJ from the gas takes place. Calculate
(a) the volume of the gas, (b) the final temperature and (c) the final pressure.