Comprehension-3
An ideal gas initially at pressure `p_(0)` undergoes a free expansion (expansion against vacuum under adiabatic conditions) until its volume is `3` times its initial volume. The gas is next adiabatically compressed back to its original volume. The pressure after compression is `3^(2//3)p_(0)`.
What is the ratio of the average kinetic energy per molecule in the final state to that in the initial state?
A. `1`
B. `3^(2//3)`
C. `3^(1//3)`
D. `3^(1//6)`