Velocity of sound in vacuum is .... $ms^{-1}$

What will be the shape of the graph of the speed of sound in air versus pressure at a constant temperature?

$A$ hospital uses an ultrasonic scanner to locate tumours in a tissue. The operating frequency of the scanner is $4.2 \, MHz$. The speed of sound in a tissue is $1.7 \, km/s$. The wavelength of sound in the tissue is close to:

At what temperature does the velocity of sound in air increase by $10\%$ compared to its velocity at $0^{\circ}C$ (in $^{\circ}C$)?

When sound waves travel from air to water,which of the following remains constant?

$A$ man stands in front of a hillock and fires a gun. He hears an echo after $1.5\, s$. The distance of the hillock from the man is ...... $m$ (velocity of sound in air is $330\, m/s$).