Sound travels in rocks in the form of

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

The speed of sound in any gas depends upon

The speed of sound in oxygen $(O_2)$ at a certain temperature is $460 \, m/s$. The speed of sound in helium $(He)$ at the same temperature will be ............. $m/s$ (assume both gases to be ideal).

The nature of sound waves in gases is

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