Diborane $(B_2H_6)$ reacts independently with $O_2$ and $H_2O$ to produce, respectively

Alumina is insoluble in water because

Electrolytic reduction of alumina to aluminium by Hall-Heroult process is carried out in the presence of

$H_3BO_3$ $\xrightarrow{{{T_1}}}X\xrightarrow{{{T_2}}}Y\xrightarrow{{red\,hot}}$ $B_2O_3$

if $T_1 < T_2$ then $X$ and $Y$ respectively are

The green colour produced in the borax bead test of a chromium$(III)$ salt is due to formation of______: