Question

The reaction
$A{g}^{2+}(aq)+Ag(s)\leftrightharpoons 2A{g}^{+}(aq)$
is an example of

• A. reduction
• B. oxidation
• C. disproportionation
• D. None of the above

Answer 1

Answer: (D)

Oxidation : - A chemical change during which an atom or ion loses electrons is called oxidation or increase in oxidation number is called oxidation.
Reduction :- A chemical change in which an atom or ion gains electrons is called reduction or decrease in oxidation number is called reduction.
Disproportionation :- If a molecule acts both as oxidising agent as well as reducing agent, then it is called auto-oxidise and the process as auto-oxidation or disproportionation.
eg, $2Pb(N{O}_3{)}_2\stackrel{\text{Heat}}{\to }2PbO+4N{O}_2+O_2$
or $\underset{+5-2}{N{O}_3^{-}}\to \underset{+4-2}{N{O}_2}+\underset{0}{O_2}$
Here $N{O}_3^{-}$ is acting as an oxidising and reducing agent.

Here $Ag$ is oxidised into $A{g}^{+}$ and $A{g}^{2+}$ is reduced into $A{g}^{+}$ .
Hence, those reaction in which two or more species undergo oxidation as well as reduction is called comproportionation.