What is a formula unit in an iconic bond

A formula unit indicates the lowest whole number ratio of ions in an ionic compound. Because the positively and negatively charged ions in an ionic compound are arranged in a crystal lattice, there is no discrete particle comparable to a molecule.

Explanation:

in chemistry, adhesion and cohesion are attractive forces that exist between molecules. they hold the molecules together from each other. they are different in that adhesive force exists between molecules of different substance while cohesive force happens between molecules of same substance.

adhesion between water and glass causes water molecules at the edge of water and glass interface to climb up the wall in a narrow glass tube. this is called capillary action. cohesion is what gives glass its shape and causes water to form a droplet.