Solve this.

5. Oxygen is 16 times heavier then hydrogen. Equal volumes of   hydrogen and oxygen are mixed. The ratio of speed of sound in the mixture to that in hydrogen is ......... 

$$\begin{gathered} 1) \sqrt{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$8$}\right.} 2) \sqrt{\frac{32}{17}} \\ 3) \sqrt{8} 4) \sqrt{\frac{2}{17}} \end{gathered}$$