Achromate ion consists of four oxygen atoms bonded to a chromium atom. it has two extra electrons. the formula of this ion:

cr4o2–

cro42+

cro42– (this one is correct by the way)

The correct answer is

Explanation:

Chromate ion is formed by the combination of one chromium atom and four oxygen atoms. The ion formed has two more electrons.

An ion which has extra electrons carries a negative charge on them and the ion which has more electrons carries a positive charge on them.

As, chromate ions have 2 extra electrons, Thus, it carries a charge of -2.

Hence, the correct answer is

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.