When $AlCl_3 \cdot 6H_2O$ is strongly heated,then it forms

In diborane $(B_2H_6)$, the number of electrons that accounts for bonding in the bridges is

Give uses of boron and its compounds.

Which one of the following is the correct statement?

$Na_2B_4O_7 \cdot 10H_2O \xrightarrow{\text{Heat}} X + NaBO_2 + H_2O$,$X + Cr_2O_3 \xrightarrow{\text{Heat}} \underset{(\text{Green coloured})}{Y}$. $X$ and $Y$ are

Identify the correct statements from the following :
$I$. $Ga_2O_3$ is an amphoteric oxide.
$II$. The dimer of aluminium chloride has three $Al-Cl-Al$ bridge bonds.
$III$. Boron is a very hard refractory solid of high melting temperature.