$(a)$ What are the basic factors on which the speed of sound in a medium depends?
$(b)$ Why are sound waves called mechanical waves?
$(c)$ How will you differentiate a high-pitch sound from a low-pitch sound with the help of a graph?

(N/A) The speed of sound in a medium depends upon:
$(i)$ Elasticity of the medium
$(ii)$ Density of the medium
$(b)$ Sound waves are called mechanical waves because they require a material medium for their propagation and are produced by the vibration of particles of the medium about their mean position.
$(c)$ The pitch of a sound depends upon its frequency. $A$ high-pitch sound has a higher frequency (more oscillations per unit time),while a low-pitch sound has a lower frequency (fewer oscillations per unit time). In the graph,the wave with more cycles per unit time represents a high-pitch sound,and the wave with fewer cycles per unit time represents a low-pitch sound.