Which oxide is alkaline?

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?

Sodium hydroxide solution reacts with phosphorus to give phosphine. To bring about this reaction,we need

Choose the correct statement$(s)$ among the following.
$A$. $SnCl_2 \cdot 2 H_2O$ is a reducing agent.
$B$. $SnO_2$ reacts with $KOH$ to form $K_2[Sn(OH)_6]$.
$C$. $A$ solution of $PbCl_2$ in $HCl$ contains $Pb^{2+}$ and $Cl^{-}$ ions.
$D$. The reaction of $Pb_3O_4$ with hot dilute nitric acid to give $PbO_2$ is a redox reaction.

The number of oxygen atoms bonded to one phosphorus atom in $P_4O_6$ is

When orthophosphoric acid is heated to $600\,^{\circ}C,$ the product formed is