During an adiabatic process , the pressure of a gas is formed to be proportional to the cube of its absolute temperature the value of r for the gas is

Question

$(a)\;\large\frac{5}{3}\qquad(b)\;\large\frac{7}{5}\qquad(c)\;\large\frac{3}{2}\qquad(d)\;\large\frac{11}{9}$