Question

how do ants indentify sweets kept in the tin

Answer 1

 Sugar has a slight odor, particularly granulated beet sugar. While all species of ants can differentiate between a wide variety of odors, the smelling range differs from a few centimeters to meters.for the food sources that ants cannot smell from a distance they 'smell' it  by touching it.  So in a way, all the food they detect, they detect it by smelling.

Answer 2

Ants can identify Sweets kept in a tin as they are capable of identifying  Fragments in the air with the help of their Antenna................