The enclosed air inside a closed box of rigid walls has pressure $P_1$. The density of air inside this box is constant. On heating the gas, the pressure of the enclosed air is increased from $P_1$ to $P_2$. Now it is observed that the sound travels $1.4$ times faster than at pressure $P_1$. The ratio $P_2/P_1$ is:

If $v_m$ is the velocity of sound in moist air and $v_d$ is the velocity of sound in dry air,under identical conditions of pressure and temperature,then:

On a windless day,sound emanates isotropically from a point source. Rays of the sound waves emanated from a point source placed close to the ground are shown in the figure. Consider horizontal wind towards the left blowing with constant velocity,which is uniform everywhere. In the following figures,rays of sound waves in the presence of the wind are shown. Which one is the most correct representation?

$Assertion :$ The base of Laplace correction was that exchange of heat between the region of compression and rarefaction in air is negligible.
$Reason :$ Air is a bad conductor of heat and the velocity of sound in air is quite large.

$A$ person in front of a mountain is beating a drum at the rate of $40$ per minute and hears no distinct echo. If the person moves $90 \, m$ closer to the mountain,he has to beat the drum at $60$ per minute to not hear any distinct echo. The speed of sound is .............. $ms^{-1}$.

The apparatus used to determine the velocity of sound in a gas is: