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

State one function each of iris,pupil,and cornea.

List four common defects of vision that can be corrected with the use of spectacles.

$A$ student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?

$A$ bifocal lens consists of both concave and convex lenses. Bifocal lenses are required by a person suffering from $.............$.
$P$ - Myopia (nearsightedness)
$Q$ - Hypermetropia (farsightedness)
$R$ - Presbyopia

List two causes leading to myopia of the eye. Draw ray diagrams to show the image formation in case of a defective eye and a corrected eye.