What happens when a ray of ordinary light is passed through a triangular glass prism?

Mark the least deviated colour in your diagram.

Why do different coloured rays deviate differently in a prism?

What will happen if another similar glass prism is placed upside down behind the first prism?

When a beam of white light is passed through a prism, it splits to form lights of seven colours. Is it possible to recombine the lights of seven colours to obtain the white light again? Explain your answer.