A ray of light travelling from a rarer medium to a denser medium

When a ray of light travels from a denser medium to a rarer medium then

If a ray of light enters from a rarer medium to a denser medium at zero angle of incidence, it would

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

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

Refraction of light, as it enters from one transparent medium to another, is due to