Which elements of group $13$, except $B$, can form tetrahedral and octahedral complex in aqueous medium ?

Give physical and chemical properties of Orthoboric acid $(H_3BO_3)$.

Aluminium trifluoride is insoluble in anhydrous $HF$ but dissolves on addition of $NaF$. Aluminium trifluoride precipitates out of the resulting solution when gaseous $BF $$_{3}$ is bubbled through. Give reasons.

Boron form covalent compound due to

$Al_4C_3$ is an ionic carbide, named as