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 sizes of the 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, and
(e ) the shape of a pulse gets distorted during propagation in a dispersive medium.

Explanation

(a) In a sound wave a point where pressrue is maximum there is said to be pressure antinode. Because of this, displacement of air particule at that point in zero and so there is said to be displacement node.
Conversely, a point where pressure is minimum there is said to be pressure node. Because of this, displacement of air particle at that point is maximum and so there is said to be displacement antinode.
(b) Bats are capable of producing and detecting ultrasonic wave (which are sound waves with frequencies greater than 20 kHz).
Dependin upon the time interval between production of ultrasonic waves nad recption of its echo, bats can estimte the distance of an object producing echo, from itself.
Also from the intensity of an echo, bats can come to know about nature and size of an object from which echo is produced.
From the time interval between successive each, bets can come to know about the direction of echo and hence location of reflector object.
(c) Though vilin and sitar produce notes of same frequency, their wave forms are different and so their qualities the different which produce differenct pleasant effects on human ear. THat is why we can distinguish between sound notes of same frequency produced by violin and sitar.
(d) Solid can sustain comprcssive as well as shearing stress. Hence both longitudinal and transverse waves can propagate in solid media. But in case of gases, they can sustain only compressive stress and so only longitudinal waves can be propagated in gases.
(e) When any pulse passes through any dispersive mediu, its wavelength changes (because of change in velocity) which changes the shape of a pulse. Hence this pulse gets distored.