The most stable form of sulphur allotrope is

Which of the following statements is $NOT$ correct about ozone?

Upon heating $KClO_3$ in the presence of a catalytic amount of $MnO_2$,a gas $W$ is formed. Excess amount of $W$ reacts with white phosphorus to give $X$. The reaction of $X$ with $HNO_3$ gives $Y$ and $Z$.
$(1)$ $W$ and $X$ are,respectively:
$[A]$ $O_3$ and $P_4O_6$
$[B]$ $O_2$ and $P_4O_6$
$[C]$ $O_2$ and $P_4O_{10}$
$[D]$ $O_3$ and $P_4O_{10}$
$(2)$ $Y$ and $Z$ are,respectively:
$[A]$ $N_2O_3$ and $H_3PO_4$
$[B]$ $N_2O_5$ and $HPO_3$
$[C]$ $N_2O_4$ and $HPO_3$
$[D]$ $N_2O_4$ and $H_3PO_3$
Give the answer of question $(1)$ and $(2)$.

Write the molecular formula of Marshall's acid.

The element which is the most abundant in the earth's crust is

In the case of hydrides of the oxygen family,which of the following physical properties changes regularly on moving down the group?