Question

Velocity of sound is maximum in-
(a). Water
(b). Oil
(c). Air
(d). Iron

Answer 1

- Hint: The speed of the sound depends on the density of the medium through which it is traveling.

Complete step-by-step solution -

Sound waves travel through a medium by longitudinal propagation. It means there are alternate contraction and expansion of particles in the medium. Its propagation mainly depends upon the density of the medium.
As the propagation of sound can be considered as the propagation of disturbance in the medium. If we talk about the case of solids, in solids, the density is more as compared to that of gases. More the density more would be the collisions. Thus more would be the disturbance. Due to the closeness of the particles, the collisions take place very quickly, and thus the sound wave travels at a higher speed.
Additional Information:
We should also talk about the dependence of the speed of sound on the density of the medium in case of gasses. Because students usually try to use the formula of the speed of sound in gases for the case of solids too. So, the formula governing the speed of sound in gases would be:
$v=\sqrt { \dfrac { \Upsilon P }{ \rho } }$
Here v is the speed of sound γ is the coefficient of adiabatic expansion, P is the pressure of the gas, and ρ is the density of the gas.
Here the density is inversely proportional to speed, unlike in the case of solids. In the case of gases, the speed of light decreases with an increase in density.

Note: Do not apply the above formula of the speed of sound in the case of solids. The reason for this is that the formula is derived by considering the motion of gas particles in a container and the gasses have more degree of freedom as compared to that of solid particles.