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

The peacock blue color is formed by the superposition of which two colors of light?

$(i)$ What is the least distance of distinct vision for a normal eye?
$(ii)$ Does the above distance increase or decrease for a long-sighted eye (hypermetropia)? Give a reason for your answer with a diagram.

$A$ 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

Which of the following statements is correct?

$A$ student sitting on the last bench can read the letters written on the blackboard but is not able to read the letters written in his textbook. Which of the following statements is correct?