$(i)$ 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.

(N/A) $(i)$ The least distance of distinct vision for a normal eye is $25\, cm$.
$(ii)$ For a long-sighted eye (hypermetropia),the least distance of distinct vision increases. $A$ person with hypermetropia cannot see objects clearly at the normal near point $(25\, cm)$ because the image is formed behind the retina. The near point of such an eye shifts further away from the eye,meaning the minimum distance at which they can see clearly is greater than $25\, cm$. This is illustrated in the diagram where the near point $N$ is at a distance greater than $25\, cm$.