give reason.

the extent of deviation of a ray of light on passing through a glass prism  depends on its colour.

The deviation of a ray of light passing through a prism depends on the refractive index of the material of the prism. It is found that refractive index is different for different color of light. It is minimum for red light and maximum for violet light. Hence, deviation is minimum of red light and maximum for violet light. Thus, the extent of deviation of a ray of light on passing through a prism depends on its color.