Question

Which one of the following is the correct statement?

• A. Boric acid is a protonic acid.
• B. Both $T{i}^{3+}andA{l}^{3+}$ ions act as oxidising agent in aqueous solution.
• C. Hydrogen bonding in $H_{3}B{O}_3$ gives it a layered structure.
• D. $B{\left(OEt\right)}_3$ imparts blue colour to the burner flamer.

Answer 1

Answer: (C)

(i) It is a weak monobasic acid soluble in water and in aqueous solution boron atom completes its octet by accepting $O{H}^{-}$ from water molecules:

$\mathrm{B}(\mathrm{OH}{)}_3+2{\mathrm{H}}_2\mathrm{O}\to {\left[\mathrm{B}(\mathrm{OH}{)}_4\right]}^{-}+{\mathrm{H}}_3{\mathrm{O}}^{+}$

(ii) Only $T{l}^{3+}$ acts as an oxidising agent on account of inert pair effect.

(iii) In the solid state, the $B{\left(OH\right)}_3$ units are hydrogen bonded together into two dimensional

sheets with almost hexagonal symmetry.



(iv) $B{\left(OEt\right)}_3$ imparts green colour to the burner flame.