Question

A spectrum is obtained by sending a beam of white light through a prism. A second prism exactly similar to the first one is placed in an inverted position with the sides parallel to the first. What will be the result?

Answer 1

when you place a second identical  prism in an inverted position with respect to the first prism, then all the colors of the spectrum will pass through the second prism. Then as a result a beam of white light will emerge from the second prism.
This what Issac Newton conducted experiments about.

Answer 2

Again a beam of white light will be obtained