Question

Identify the correct statements from the following:
(i) In orthoboric acid, boron is in planar geometry
(ii) $In BCl _{3} . NH _{3}$, boron has tetrahedral geometry
(iii) Aqueous solution of borax is acidic

• A. (i), (ii)
• B. (ii), (iii)
• C. (i), (iii)
• D. (i), (ii), (iii)

Answer 1

Answer: (A)

(i) In orthoboric acid $\left( H _{3} BO _{3}\right)$ is boron $s p^{2}$ hybridised. It forms three bonds with three hydroxyl group which lie on the same plane. Thus, in orthoboric acid, boron is in planar geometry, thus statement is correct.

(ii) $BCl _{3}$ is a non-polar molecule with a symmetrical distribution of electrons and flat geometry. It forms a polar non-covalent bond with $NH _{3}$ molecule due to presence of empty orbital in boron and lone pair of electrons over $N$ -atom, which has tetrahedral geometry. Thus, statement is correct.

(iii) Borax is a salt of a strong base and a weak acid $\left( H _{3} BO _{3}\right)$. Hence, it is basic in nature. Thus, this statement is incorrect.