What about from glass to air ?

What happens while it goes from glass to air ?

Light obliquely travel from glass to air , critical angle of glass is 42^@ . What happens to the ray ofd light when the angle of incidence is 45^@ ? Explain the phenomenon ?

Light obliquely travel from glass to air , critical angle of glass is 42^@ . What is mean by critical Angle ? In which phenomenon we observe the incident angle is 40^@ ? Explain the phenomenon ?

Light obliquely travel from glass to air , critical angle of glass is 42^@ . Angle of incidence is 42^@ find its refracted angle ?

What about the factors of 240 ?