Which of the following oxides is strongly basic?

Inorganic graphite is:

Match the following:

Column $I$	Column $II$
$A$. $Bi^{3+} \longrightarrow (BiO)^{+}$	$P$. Heat
$B$. $[AlO_2]^{-} \longrightarrow Al(OH)_3$	$Q$. Hydrolysis
$C$. $SiO_4^{4-} \longrightarrow Si_2O_7^{6-}$	$R$. Acidification
$D$. $(B_4O_7^{2-}) \longrightarrow [B(OH)_3]$	$S$. Dilution by water

Aluminum dissolves in mineral acids and aqueous alkalis and thus shows amphoteric character. $A$ piece of aluminum foil is treated with dilute hydrochloric acid or dilute sodium hydroxide solution in a test tube and on bringing a burning match stick near the mouth of the test tube,a pop sound indicates the evolution of hydrogen gas. The same activity when performed with concentrated nitric acid,the reaction does not proceed. Explain the reason.

$A$ 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 is not true about borax?