Question

Calculate the ratio of the speed of sound in neon to that in water vapour at any temperature. Given that molecular weight of neon gas $=2.02\times {10}^{-2}kg{mole}^{-1}$ and molecular weight of water vapour $=1.8\times {10}^{-2}kg{mole}^{-1}$.

Answer 1

Speed of sound in gas $v=\sqrt{\frac{\gamma RT}{M}}$
$⟹$ $\frac{v_n}{v_w}=\sqrt{\frac{M_w}{M_n}}$ $(\because \gamma ,R,T$ are constants $)$
Given : $M_w=1.8\times {10}^{-2}kg/mol$ and $M_n=2.02\times {10}^{-2}kg/mol$
So, $\frac{v_n}{v_w}=\sqrt{\frac{1.8}{2.02}}=0.94$