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

In the nitrogen family,the $H-M-H$ bond angle in the hydrides $MH_3$ gradually becomes closer to $90^o$ on going from $N$ to $Sb$. This shows that gradually

Which of the following is used as an anesthetic?

What are neutral oxides? Give examples.

How does concentrated $HNO_3$ react with aluminium?

$A$ colourless,neutral,paramagnetic oxide of nitrogen '$P$' on oxidation gives reddish brown gas $Q$. $Q$ on cooling gives colourless gas $R$. $R$ on reaction with $P$ gives blue solid $S$. Identify $P, Q, R, S$ respectively.