Light

Question 1

Concave or diverging lens

Answer 1

Used to spread Rays apart

Used to fix short sightedness, or myopia

Question 2

White light

Answer 2

White light is not really white
It is a mixture of the 7 colours of the spectrum
Dispersion is the splitting of white light into its constitution colours due to refraction

Question 3

Convex or converging lens

Answer 3

Used to bring rays together

Used to fix long sightedness, or hypermetropia