Which furnace is used to extract iron metal from its ore?

What is the chemical formula of sodium sulfite?

Make the correct pairs from below mentioned $X$ and $Y$:

$X$	$Y$
$1$. Extraction of sulphur	$p$. Contact process
$2$. Production of nitric acid	$q$. Frasch method
$3$. Production of sulphuric acid	$r$. Haber's process
$4$. Production of ammonia gas	$s$. Ostwald's method

An element $A$ reacts with water to form a compound $B$ which is used in white washing. The compound $B$ on heating forms an oxide $C$ which on treatment with water gives back $B$. Identify $A$,$B$ and $C$ and give the reactions involved.

An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be:

Which of the following metals are obtained by electrolysis of their chlorides in molten state?
$(i)$ $Na$
$(ii)$ $Ca$
$(iii)$ $Fe$
$(iv)$ $Cu$