Question

Match the following reactions (in Column I) with processes (Column II).

Answer 1

When the oxidation number of C increases, it undergoes oxidation and when the oxidation number of C decreases, it undergoes reduction. If there is no change in the oxidation number of C, then there is neither reduction nor oxidation.
(A) $\stackrel{-4}{C}{H}_4⟶\stackrel{-2}{C}{H}_{3}OH$
(Increase in oxidation number from -4 to -2) (Oxidation)
(B) $\stackrel{0}{C}{H}_2{Cl}_2⟶\stackrel{0}{C}{H}_{2}O$
(Oxidation number is zero for both) (Neither)
(C) $\stackrel{-2}{C}{H}_2=\stackrel{-2}{C}{H}_2⟶H_3\stackrel{-3}{C}-\stackrel{-3}{C}{H}_3$
(Decrease in oxidation number from -2 to -3 for both $C$) (Reduction)
(D) The oxidation number of both $C$'s has change one from $-1$ to $-3$ and in the other from $-1$ to $+1$.
Thus, the average value is compared for both reactant and product, which is $-1$. It has remained unchanged, so it is neither.
$C_2{H}_2⟶C{H}_{3}CHO$
$2x+2=0$ $2x+4-2=0$
$x=-1$ $x=-1$