Explain why (or how) `:` (a) In a sound wave, a displacement node is a pressure antinode and vice-versa,
(b) Bats can ascertain distances, directions, nature and size of obstacles without any eyes,
(c) a violin note and sitar note may have the same frequency, yet we can distinguish between the two notes, (d) Solids can support both longitudinal and transverse waves, but only longitudinal waves can propagate in gases,
(e) The shape of pulse gets distorted during propagation in a dispersive medium.

Explanation

(i) Solution needed.
(ii) Bats emit ultrasonic waves of large frequencies (small wavelength) when they fly. These ultrasonic waves are received by them after reflection from the obstacle. Their ears are so sensitive and trained that they not only get the information of the distance of the obstacle but also that of the nature of the reflecting surface.
(iii) The quality of the sound produced by an instrument depends upon the number of overtones. Since the number of overtones is different in the cases of sounds produced by violin and sitar therefore we can distinguish through them.