Bats can ascertain distances, directions, nature and size of the obstacle without any eye, explain how ?

Explain why (or how) : (a) In a sound wave, a displacement node is a pressure antinode an dvice-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.

Bats can ascrtain distance, directions, nature and size of the ohstacles at night. This is possible by reflection of the emitted

Is there any device by which direct current can be controlled without any loss of energy ? Can a choke coil do so?

"Natural selection can lead to stabilization, directional change and disruptive changes." Explain the terms stabilization, directional change and disruptive change mentioned above.

The abnormally smaller size of Ga among its group can be explained by -

In Fraunhofer diffraction experiment, L is the distance between screen and the obstacle, b is the size of obstacle and lambda is wavelength of incident light. The general condition for the applicability of Fraunhofer diffraction is :