Which of the following statements is true about the movement of sound waves?

a. they can only travel through a vacuum
b. they can travel through air only
c. they can only travel through a medium
d. they travel fastest in gaseous mediums

The correct option is C.

Explanation:

Longitudinal wave is a wave in which the particles vibrates parallel to the direction of the energy transportation of the wave .

For example, sound wave.

Sound wave consists of rarefaction and compression. In rarefaction, the density of the particles is more in comparison to compression.

Sound wave needs a medium for its propagation. It can travel in solid, liquid and gas. It cannot travel in vacuum.

Therefore, the true statement about the movement of sound waves is only (C) option.

not really sure but thinking 1.54 mm/us