In a certain liquid, the speed of yellow light is 2.4 × 10^8 m s^...

The refractive index of a medium is given by the ratio of the speed of light in vacuum to the speed of light in the medium.

$n = \dfrac{c}{v}$

Given the speed of yellow light in the liquid, $v = 2.4 \times 10^8 \text{ m s}^{-1}$

The speed of light in vacuum is $c = 3.0 \times 10^8 \text{ m s}^{-1}$

Substituting the values:

$n = \dfrac{3.0 \times 10^8}{2.4 \times 10^8}$

$n = \dfrac{3.0}{2.4} = \dfrac{5}{4} = 1.25$