The coloured light having the maximum speed in glass prism is:(a) blue (b) green (c) violet (d) yellow

In the spectrum of white light, Red light has the longest wavelength and the least frequency (least deviation), which means it has a maximum speed, whereas, violet light has the shortest or least wavelength and the highest frequency (maximum deviation), which means it has the minimum speed among all the colours in the visible spectrum.

As we go from red to violet (top to bottom) the wavelength and speed keep on decreasing while the frequency keeps increasing. Thus, among the given colour of light, yellow would have the greatest wavelength.