question_answer

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

A)  reduction

B)  oxidation

C)  disproportionation

D)  None of the above

Correct Answer: D

Solution :

                 Key Idea 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, \[2Pb{{(N{{O}_{3}})}_{2}}\xrightarrow{Heat}2PbO+4N{{O}_{2}}+{{O}_{2}}\] or            \[\underset{+5-2}{\mathop{NO_{3}^{-}}}\,\xrightarrow{{}}\underset{+4\,\,-2}{\mathop{N{{O}_{2}}}}\,+\underset{0}{\mathop{{{O}_{2}}}}\,\] Here \[NO_{3}^{-}\] 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.