$SONAR$ emits which of the following waves?

The nature of sound waves in gases is

Explain the propagation of sound waves in:
$(i)$ air
$(ii)$ solids

What is called rarefaction? Which type of changes in density and pressure take place in it?

The sound carried by air from a sitar to a listener is a wave of the following type:

The echo of a gun shot is heard $8 \, s$ after the gun is fired. How far from the shooter is the surface that reflects the sound (in $, m$)? (Velocity of sound in air $= 350 \, m/s$)