2NaOH + Zn → Na₂ZnO₂ + H₂

Explanation- When metal react to base then metallic salt and hydrogen (H₂) gas are formed.

Balancing of chemical equation-

(i) Here one Na atom is in left side and 2 Na atom are in right side. So to equate the Na atoms, we will multiply in NaOH by 2.

2NaOH + Zn → Na₂ZnO₂ + H₂

(ii) And we shall check that other atoms are equal or not. If the other atoms are equal to both side then the equation is balanced. If the other atoms are not equal then we shall make them equal.

Now Na atoms are equal, Zn atoms are equal, H atoms are equal and O atoms are also equal on both sides. So the chemical equation is balanced.