During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its absolute temperature. The ratio of \(\displaystyle \frac{C_P}{C_V} \) for the gas is:
\(\displaystyle \frac{7}{5} \)
\(\displaystyle \frac{3}{2} \)
\(\displaystyle \frac{9}{7} \)
\(\displaystyle \frac{5}{3} \)