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?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$ : $PH_3$ has lower boiling point than $NH_3$.
Reason $(R)$ : In liquid state $NH_3$ molecules are associated through van der Waals forces,but $PH_3$ molecules are associated through hydrogen bonding.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which of the following acids forms two series of salts?

The correct order of reducing ability of the following hydrides is:

Which of the following oxyacids is the strongest acid?

Which of the following substances is a deliquescent ionic solid?