Which of the following is isostructural with graphite?

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$:
$\underline{B}F_3 + 3H_2O \longrightarrow H_3BO_3 + 3HF$

In the borax bead test,which of the following compounds is formed?

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.

In the following reaction,assign the correct description for the underlined atom in the product of complete hydrolysis at $R.T.$:
$\underline{I}Cl + H_2O \longrightarrow HIO + HCl$

$A$ group $13$ element '$X$' reacts with chlorine gas to produce a compound $XCl_3$. $XCl_3$ is electron deficient and easily reacts with $NH_3$ to form $Cl_3X \leftarrow NH_3$ adduct,however,$XCl_3$ does not dimerize. $X$ is