The element that has the least metallic character is ..........

The total number of acidic oxides from the following list is: $NO$,$N_2O$,$B_2O_3$,$N_2O_5$,$CO$,$SO_3$,$P_4O_{10}$

The reason for boric acid being polymeric is .....

Which of the following is a true alum?

Diborane reacts with $HCl$ in the presence of $AlCl_3$ and liberates:

$Na_2B_4O_7 \cdot 10H_2O \xrightarrow{\Delta} 2NaBO_2 + B_2O_3 (A) + 10H_2O$. $(A) + MnO \xrightarrow{\Delta} Mn(BO_2)_2 (B)$. $(A)$ and $(B)$ are