Which of the following oxides of nitrogen is paramagnetic?

In some of the reactions,thallium resembles aluminium,whereas in others,it resembles group $1$ metals. Support this statement by giving some evidence.

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?

Phosphorus pentachloride $(PCl_{5})$:

How many compounds given below are amphoteric oxides?
$P_2O_5, P_4O_6, As_2O_5, As_4O_6, Sb_2O_5, Sb_4O_6, Bi_2O_3$

The basicity of $H_3PO_2, H_3PO_3, H_3PO_4$ respectively is