$Al_2O_3$ reacts with

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.

What is the correct order of melting points for the elements of group $13$?

The correct statements from the following are:
$(A)$ Ionic radii of trivalent cations of group $13$ elements decrease down the group.
$(B)$ Electronegativity of group $13$ elements decreases down the group.
$(C)$ Among the group $13$ elements, Boron has the highest first ionisation enthalpy.
$(D)$ The trichlorides and triiodides of group $13$ elements are covalent in nature.
Choose the correct answer from the options given below:

Write the preparation of diborane and describe its physical and chemical properties.

Borax is converted into crystalline boron by the following steps :
$Borax$ $\xrightarrow{HCl} (X)$ $\xrightarrow{\Delta} B_2O_3$ $\xrightarrow{\Delta, Y} B$
Identify $X$ and $Y$ respectively.