If 2 moles of diatomic gas and 1 mole of monoatomic gas are mixed , then ratio of specific heats $\;\large\frac{C_{p}}{C_{v}}\;$ is

Question

$(a)\;\large\frac{7}{3}\qquad(b)\;\large\frac{5}{4}\qquad(c)\;\large\frac{19}{13}\qquad(d)\;\large\frac{15}{19}$