Difference in speed of monochromatic red light and violet light in a prism?

Hello Harjyot, the frequency character never changes as light travels from one medium into another.
Only its speed changes and so its wavelength has to change.
Now different colours would have different fall in the speed. Red would have only a less fall but violet has larger fall. So violet travels slower than red in the glass medium.
So refractive index of glass for violet would be more than that for red.
(recall refractive index = speed of light in vacuum/ speed of light in the medium)
So the beauty is that all the colours would have the same speed in vacuum viz 3*10^8 m/s