Which one of the following statements about H3BO3 is not correct ?
It is a tribasic acid
It is prepared by acidifying an aqueous solution of borax
It has a layer structure in which planar BO3 units are joined by hydrogen bonds
It does not act as proton donor as it acts as a Lewis acid by accepting hydroxyl ion
H3BO3 is weak monobasic acid
Boric acid has a layer structure in which planar BO3 units are joined by: