Question

Why boric acid considered as a weak acid..?

Answer 1

Boric acid is considered as a weak acid as it contains lower concentration of hydrogen atoms as compared to other acids with equal concentration of water .Plus is shows lower acidity number on a P.H. scale (7-10).

Hope It Helped .

Answer 2

Boric acid is a ‘weak acid’ because it has very less tendency to release $\bold{\mathrm{H}^{+}}$ ions. It is a Lewis acid as B is electron deficient here and therefore it can accept hydroxyl ion from water to complete its octet.

Overall we can say that it is a aprotic acid but only a Lewis acid due to electron deficient nature of boron therefore it accepts electrons from hydroxyl ions to complete its octet.  

The ‘structure of Boric acid’ is given in below attached image.