For a gas $\large\frac{R}{C_v}$$ = 0.67$ the gas may be

Question

$(a)\;H_2\qquad(b)\;Ar.\qquad(c)\;O_3\qquad(d)\;H_2O_2$

Answer 1

Given

$\large\frac{R}{C_v} = 0.67$

$(or) \large\frac{C_p - C_v}{C_v} = 0.67$

$(or) \large\frac{C_p}{C_v} - 1 = 0.67$ (or)

$\gamma = 1.67$

Thus gas is monoatomic , i.e Ar

Hence answer is (b)