Question

Why are the aqueous solution of NaHCO3 and Na2CO3 basic in nature?

Answer 1

they are basic in nature as the give OH- ions on dissolving in water

Answer 2

Bases are the type of chemical compounds which produces OH ion when it dissolves in the water.

And, according to the question;

The NaHCO3 and the Na2CO3 are already have base like physical characteristics, these compounds also produce OH ion in the water

That's why,the aqueous solution of NaHCO3 and Na2CO3 are basic in nature.