Boron forms covalent compounds due to:

$A$ 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.

In $B_2H_6$:

Aluminium reacts with dilute $HCl$ and liberates a gas '$A$' and with aqueous alkali liberates a gas '$B$'. $A$ and $B$ respectively are

In a molecule of pyrophosphoric acid $(H_4P_2O_7)$,the number of $P-OH$,$P=O$ and $P-O-P$ bonds/moiety(ies) respectively are:

What is the molecular formula of borazole?