$\rho_{\mathrm{m}}=\frac{4 \mathrm{V} \times 1+\mathrm{V} \times 16}{5 \mathrm{V}}=4$
i.e., density of mixture is 4 times that of hydrogen. $\mathrm{As}$
$\mathrm{V} \propto(1 / \rho)^{1 / 2}$
Velocity in mixture $=\frac{1270}{(4)^{1 / 2}}=635 \mathrm{\,m} / \mathrm{s}$


| $(A)$ Temperature of gas is made $4$ times and pressure $2$ times | $(P)$ speed becomes $2\sqrt 2$ times |
| $(B)$ Only pressure is made $4$ times without change in temperature | $(Q)$ speed become $2$ times |
| $(C)$ Only temperature is changed to $4$ times | $(R)$ speed remains unchanged |
| $(D)$ Molecular mass of the gas is made $4$ times | $(S)$ speed remains half |
$y = 0.02sin\left[ {2\pi \left( {\frac{t}{{0.04\left( s \right)}} - \frac{x}{{0.50\left( m \right)}}} \right)} \right]m$ The tension in the string is .... $N$
$\left[\right.$ Gain in $\left. dB =10 \log _{10}\left(\frac{ P _{0}}{ P _{i}}\right)\right]$