$A$ man standing on a cliff claps his hands and hears the echo after $1 \, s$. If the sound is reflected from another mountain and the velocity of sound in air is $340 \, m/s$,then the distance between the man and the reflection point is ..... $m$.

At what temperature is the velocity of sound double that of its velocity at $0^{\circ}C$?

$A$ 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 .............. $ms^{-1}$.

What is called compression or condensation? Which type of changes in density and pressure take place in it?

$A$ man sets his watch by the sound of a siren placed at a distance of $1 \,km$ away. If the velocity of sound is $330 \,m/s$,what is the status of his watch?

Obtain the equation for the speed of a sound wave in air and identify the error in this equation.