Question

Which of the following statements about $H_{3}B{O}_3$ is not correct?

• A. It is a strong tribasic acid
• B. It is prepared by acidifying an aqueous solution of borax
• C. It has a layer structure in which planar $B{O}_3$ units are joined by hydrogen bonds
• D. It does not act as proton donor but acts as a Lewis acid by accepting hydroxyl ion

Answer 1

Answer: (A)

Boric acid $(H_{3}B{O}_3)$ is a weak monobasic acid with $K_a=1.0\times 10^{-9}$. It may be noted that boric acid does not act as a protonic acid (i.e. proton donor) but behaves as a Lewis acid by accepting a pair of electrons from $O{H}^{-}$ ion. $B(OH{)}_{3}3+2H-O-H⟶[B(0H{)}_4{]}^{-}+H_3{O}^{+}$