Question

An iron nail is opaque body

Answer 1

Here is your answer.

It is opaque body as most of iron and steel does not allow light to pass through.

hope you understand it..

Answer 2

Opaque body/object are anything that DOES NOT ALLOW LIGHT TO PASS THROUGH .... that being said it obviously means that we can’t even see through it
So... yes AN IRON NAIL IS AN OPAQUE BODY