Newton assumed that sound propagation in a gas takes place under which condition?

Sound waves travel fastest in

Which of the following is not a transverse wave?

Sound travels in rocks in the form of

Mention the audible frequency range for humans.

The figure represents the instantaneous picture of a longitudinal harmonic wave travelling along the negative $x$-axis. Identify the correct statement$(s)$ related to the movement of the points shown in the figure. The points of maximum rarefaction are