Identify the correct statement from the following.

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 $(2)$.

Which of the following options is $incorrect$?

When a small amount of $KMnO_4$ is added to concentrated $H_2SO_4$,a green oily compound is obtained which is highly explosive in nature. The compound is:

Which of the following elements shows polymorphism?

Elements of group $16$,except $Po$,are known as chalcogens because .........