Why do astronauts talk to each other through radio telephones?

Write true or false for the following statement: Sound produced by a sounding body of frequency $300 \text{ Hz}$ covers $34 \text{ m}$ in the time the sounding body produces $30$ vibrations.

Answer the following:
$(i)$ Can transverse waves travel in gases?
$(ii)$ Can longitudinal waves travel in solid,liquid as well as gas?
$(iii)$ At any instant,a compression is formed at a point. After how much time $(a)$ a rarefaction $(b)$ a compression will be formed at the same point?

$(a)$ What is the cause of the sensation of sound due to the rolling of thunder?
$(b)$ Give the audible range of the human ear.
$(c)$ What are infrasonic and ultrasonic waves?

$A$ bomb explodes on the Moon. How long will the sound of the explosion take to reach the Earth?

$(a)$ Illustrate the use of a stethoscope.
$(b)$ What are infrasonic and ultrasonic sound waves?