Chemistry - Complete Pblock- Question with Solution | TestHub

A. Boric acid is a very weak acid. In the presence of polyhydroxy compounds (sugars), it forms a strong monobasic acid, allowing for a sharp endpoint with NaOH.

B. Borax solution is alkaline due to hydrolysis and acts as a buffer.

C. ${\mathrm{B}}_2{\mathrm{H}}_6$ reacts with excess $\mathrm{N}{\mathrm{H}}_3$ at low temperatures to form an ionic compound, $[\mathrm{B}{\mathrm{H}}_2(\mathrm{N}{\mathrm{H}}_3{)}_2{]}^{+}[\mathrm{B}{\mathrm{H}}_4{]}^{-}$. On heating, it gives borazine (${\mathrm{B}}_3{\mathrm{N}}_3{\mathrm{H}}_6$), which is aromatic but more reactive than benzene. Thus, statement C is incorrect.

D. Hydrolysis of $\mathrm{B}{\mathrm{F}}_3$ yields boric acid and fluoroboric acid (which forms fluoroborates).

The final answer is $\boxed{A,B,D}$