What happens when an oblique ray of light enters from glass into air?

For the same angle of incidence in media $P, Q$ and $R$,the angles of refraction are $45^{\circ}, 35^{\circ}$ and $15^{\circ}$ respectively. In which medium will the velocity of light be minimum? Give reason.

Which type of an image is formed by a plane mirror?

The angle between an incident ray and the reflected ray is $70^{\circ}$ as shown in the figure. What is the value of $\theta$?

What is the angle of incidence for a light ray incident on a glass slab such that it does not undergo refraction (in $^{\circ}$)?

Where is the image formed when an object is placed between the principal focus $(F)$ and the center of curvature $(C)$ of a concave mirror?