A diatomic gas expands adiabatically to a volume 1.35 times larger than the initial volume.?

Question

The initial temperature is 18 C.Find the final temperature.

Answer 1

Assuming the process is also reversible,
T_1 * V_1^(k-1) = T_2 * V_2^(k-1) where k = cp/cv ~ 1.4 for diatomic gases.

V_2 = 1.35 V_1, and Temps are absolute.

Crank it out.