$P_4 O_{10}$ is the anhydride of

Which of the following is a colorless gas with a rotten fish-like smell?

Which element does not form complexes?

$\underbrace{2NO + O_2}_{(X)} \rightleftharpoons \underbrace{2NO_2}_{(Y)} \underset{heat}{\overset{cold}{\longleftrightarrow}} \underbrace{N_2O_4}_{(Z)}$
$X, Y$ and $Z$ can be described as:

In the Ostwald process for the manufacture of $HNO_3$,which of the following is used as a catalyst?

Match the following:

$a$. Pure nitrogen	$i$. Chlorine
$b$. Haber process	$ii$. Sulphuric acid
$c$. Contact process	$iii$. Ammonia
$d$. Deacon's process	$iv$. Sodium azide or Barium azide

Which of the following is the correct option?