Air at $820$ K and an initial volume of $0\mathrm{.}1m^3$ is enclosed in a cylinder. The air expands isentropically against a piston, and the volume of the air increases to $0\mathrm{.}300m^3.$ Using the ideal gas tables for air, find:

a$)$ the temperature of the air at the end of the isentropic process and

b$)$ compute the work done per unit mass by the gas during the process