Which of the following statements is true about $H_3BO_3$?

Boron cannot form which one of the following anions?

For the following halides: $(1) \ BCl_3$,$(2) \ AlCl_3$,$(3) \ GaCl_3$,$(4) \ InCl_3$,what is the decreasing order of their Lewis acid strength?

Select the correct statement about the hydrolysis of $BCl_3$ and $NCl_3$.

Write the chemical reaction of $Al$ with aqueous alkali.

The crystalline form of borax has
$(A)$ tetranuclear $\left[B_4O_5(OH)_4\right]^{2-}$ unit
$(B)$ all boron atoms in the same plane
$(C)$ equal number of $sp^2$ and $sp^3$ hybridized boron atoms
$(D)$ one terminal hydroxide per boron atom