In the combination reaction, two reactants combine to form 1 product.
$
\mathrm{Mg}+\mathrm{N}_2 \longrightarrow \mathrm{Mg}_3 \mathrm{~N}_2
$
So, A of list-I matches with (iii) of list-II.
In the decomposition reaction, one reactant decomposes into multiple products.
$
\mathrm{KClO}_3 \longrightarrow \mathrm{KCl}+\mathrm{O}_2
$
So, B of list I matches with (iv) of list II.
A disproportionation reaction is a redox reaction in which one species undergoes both oxidation and reduction.
$
\mathrm{Cl}_2 \longrightarrow \mathrm{Cl}^{-}+\mathrm{ClO}_3^{-}
$
So, C of list I matches with (ii) of list II.
When components of two ionic compounds are swapped, two new compounds are formed. This is double displacement reaction.
$
\mathrm{AgNO}_3+\mathrm{CaCl}_2 \longrightarrow \mathrm{CaNO}_3+\mathrm{AgCl}_2
$
So, D of list I matches with (i) of list II.
Hence the correct match is
A-(iii), B-(iv), C-(ii), D-(i)
