Question

Which of the following is not a disproportionation reaction:

• A. $P_4+NaOH\to Na{H}_{2}P{O}_2+P{H}_3$
• B. $Ba{C}_2+N_2\to Ba\left(C{N}_2\right)$
• C. $H{g}_2{I}_2\to Hg{I}_2+Hg$
• D. $Ca(OH{)}_2+C{l}_2\to CaOC{l}_2+H_{2}O$

Answer 1

The correct option is B $Ba{C}_2+N_2\to Ba\left(C{N}_2\right)$

The reactions in which a single reactant is oxidized and reduced is known as disproportionation reaction.
$\left(A\right)\stackrel{\left(0\right)}{P_4}+NaOH\to Na{H}_2\stackrel{(+5)}{P}{O}_4+\stackrel{(-3)}{P}{H}_3$
$\left(B\right)\stackrel{(-1)}{Ba{C}_2}+\stackrel{\left(0\right)}{N_2}+\to Ba\stackrel{(+2)(-3)}{(CN{)}_2}$
$\left(C\right)\stackrel{(+1)}{H{g}_2}{I}_2\to \stackrel{(+2)}{Hg}{I}_2+\stackrel{\left(0\right)}{Hg}$
$\left(D\right)Ca(OH{)}_2+\stackrel{0}{C{l}_2}\to CaO\stackrel{+1and-1}{C{l}_2}+H_{2}O$
Although reaction (b) is a redox reaction, this isn't an example of disproportionation reaction as no single reactant doesn't undergo reduction and oxidation simultaneously.