$Na_2B_4O_7$ $\xrightarrow{x} H_3BO_3$ $\xrightarrow{\Delta} B_2O_3$ $\xrightarrow{y} B$
Here $X$ and $Y$ are respectively:

Match the following compounds in List-$I$ with their uses in List-$II$:

List-$I$ (Compounds)	List-$II$ (Uses)
$A$. Boron-$10$	$I$. Antiseptic
$B$. Borax	$II$. Bullet proof vest
$C$. Boron-fibre	$III$. Neutron absorber
$D$. Orthoboric acid	$IV$. Heat resistance glasses

Boron does not form $B^{3+}$ cation easily. It is due to

Identify the $P$ and $Q$ of the following reaction: $P + Q \longrightarrow [B(OH)_4]^{-} + H_3O^{+}$

$A$ black coloured element with $ns^2 np^1$ outer electronic configuration cannot react with air in its crystalline form. However,in amorphous form,it gives an oxide in air which is acidic in nature. Identify the element.

Which of the following structures is similar to graphite?