Question

Carbonate ion is a __________ ion.

• A. monovalent
• B. trivalent
• C. divalent
• D. pentavalent

Answer 1

The correct option is C divalent

A carbonate ion consists of one atom of carbon and three atoms of oxygen. It has two unit negative charge.
The formula of carbonate ion is $C{O_3}^{2-}$. Since, the charge on the carbonate ion is -2, it is known as divalent ion.