The densities of two diatomic gases at constant temperature and pressure are $d_1$ and $d_2$. The ratio of the speed of sound in these gases is:

$A$ man,standing between two cliffs,claps his hands and starts hearing a series of echoes at intervals of one second. If the speed of sound in air is $340 \, ms^{-1}$,the distance between the cliffs is .... $m$

Earthquakes generate sound waves inside the earth. Unlike a gas,the earth can experience both transverse $(S)$ and longitudinal $(P)$ sound waves. Typically,the speed of $S$ wave is about $4.0 \; km/s$,and that of $P$ wave is $8.0 \; km/s$. $A$ seismograph records $P$ and $S$ waves from an earthquake. The first $P$ wave arrives $4 \; min$ before the first $S$ wave. Assuming the waves travel in a straight line,at what distance (in $km$) does the earthquake occur?

Sound waves travel fastest in

$Assertion :$ The change in air pressure affects the speed of sound.
$Reason :$ The speed of sound in gases is proportional to the square of pressure.

$A$ train,standing in a station yard,blows a whistle of frequency $400 \, Hz$ in still air. The wind starts blowing in the direction from the yard to the station with a speed of $10 \, m/s$. Given that the speed of sound in still air is $340 \, m/s$. Mark the $INCORRECT$ statement: