Question

why is normal eye not able to see clearly the object placed closer than 25 cm​

Answer 1

This is because the ciliary muscles of eyes are unable to contract beyond a certain limit. If the object is placed at a distance less than 25cm from the eye, then the object appears blurred because light rays coming from the object meet beyond the retina

Answer 2

A normal eye cannot see clearly the object placed closer than 25 cm because it is tough for the eyes to see that is too near of it