Among the following statements, the correct statement for a wave is

Given below are some examples of wave motion. State in each case if the wave motion is transverse,longitudinal or a combination of both:
$(a)$ Motion of a kink in a longitudinal spring produced by displacing one end of the spring sideways.
$(b)$ Waves produced in a cylinder containing a liquid by moving its piston back and forth.
$(c)$ Waves produced by a motorboat sailing in water.
$(d)$ Ultrasonic waves in air produced by a vibrating quartz crystal.

Provide an example of a spring for wave propagation.

Mechanical waves on the surface of a liquid are

Sound waves exhibit more diffraction than light waves because:

$A$ person outside a room can hear the conversation happening inside the room because of...