Which one of the following statements is correct regarding the travel of a light beam from a rare to a dense medium?

Which one of the following statements is not correct for light rays ?

When a light beam falls on a triangular glass prism, a band of colours is obtained. Which one of the following statements is correct in this regard ?

Which one of the following statements about the aperture of a convex lens is correct?

Which one of the following statement is not correct?

Which of the following does not change when light travels from one medium to another?