The colour of which part of the eye determines the colour of the eye of a person?

In the eye of a person suffering from myopia (nearsightedness),where is the image of a distant object formed?

Dispersion of white light occurs because every colour travels with a different speed in a transparent medium.

What is the least distance of distinct vision of a normal human eye (in $cm$)?

$(a)$ How does refraction take place in the atmosphere? Why do stars twinkle but not the planets?
$(b)$ State any two effects of atmospheric refraction on the sun as observed from the Earth.

Draw a neat diagram to show the refraction of a light ray through a glass prism,and label on it the angle of incidence,and angle of deviation.