Buckminister fullerene contains the following $X$ number of six and $Y$ number of five member rings. What is the value of $X$ and $Y$ ?

The number of dissociable protons in "orthophosphoric acid" is

Decreasing order of number of ionisable hydrogen atoms in the following molecules is

I. $\mathrm{H}_3 \mathrm{PO}_4$

II. $\mathrm{H}_3 \mathrm{PO}_3$

III. $\mathrm{H}_3 \mathrm{PO}_2$

IV. $\mathrm{H}_4 \mathrm{P}_2 \mathrm{O}_6$

When orthoboric acid $\left(\mathrm{H}_3 \mathrm{BO}_3\right)$ is subjected to strong heating, the residue left is