7407/2 Physics Jun 2018 Quiz | AQA AS Level MCQ

A ray of light is incident on the internal boundary of a rectangular glass block in air.
Part of the light refracts out of the block at an angle of 30°.
Some of the remaining light reflects within the block to become incident on the right-hand boundary.
refractive index of glass = 1.48
What is the angle of incidence of the ray at the right-hand boundary?