Through which part of the eye do light rays from an object first enter the eye?

What is meant by scattering of light? Use this phenomenon to explain why the clear sky appears blue or the sun appears reddish at sunrise.

What is the time difference between the actual sunset and the apparent sunset?

Mention the factor on which scattering of light depends. Why does the sky appear dark in space?

$(i)$ What is meant by dispersion of white light? Draw a diagram to show the dispersion of white light by a glass prism.
$(ii)$ Light of two colours $A$ and $B$ pass through a prism. $A$ deviates more than $B$ from its path of incidence. Which colour has a higher speed in the prism?

$(a)$ With the help of a suitable diagram,explain why the Sun is visible to us two minutes before the actual sunrise and two minutes after the actual sunset.
$(b)$ Name the phenomenon responsible for the apparent flattening of the Sun's disc at sunrise and sunset.