In the extraction of aluminium the electrolyte is

Describe the shapes of $BF $$_{3}$ and $BH _{4}^{-}$. Assign the hybridisation of boron in these species.

Covalent electron deficient hydride is formed by

Anhydrous aluminium chloride fumes in moist air owing to the formation of

The crystalline form of borax has

($A$) tetranuclear $\left[\mathrm{B}_4 \mathrm{O}_5(\mathrm{OH})_4\right]^{2-}$ unit

($B$) all boron atoms in the same plane

($C$) equal number of $s p^2$ and $s p^3$ hybridized boron atoms

($D$) one terminal hydroxide per boron atom

Which of the following is only acidic in nature