The chemical symbol for sodium zincate is Na2ZnO2. This can be derived from the valencies of the constituent elements.

Sodium (Na) has a valency of +1, while zinc (Zn) has a valency of +2. Oxygen (O) has a valency of -2.

To form a neutral compound, the total positive charges must equal the total negative charges. In this case, we need two sodium ions (2 × +1 = +2) to balance the charge of one zinc ion (+2) and two oxide ions (2 × -2 = -4).

Therefore, the chemical symbol for sodium zincate is Na2ZnO2.