Which reaction does not represent auto redox or disproptionation?

Options

A. `Cl_(2)+OH^(-)rarrCl^(-)+ClO_(3)^(-)+H_(2)O`
B. `2H_(2)O_(2)rarr2H_(2)O+O_(2)`
C. `2Cu^(+)rarrCu^(2+)+Cu`
D. `(NH_(4))_(2)Cr_(2)O_(7)rarrN_(2)+Cr_(2)O_(3)+4H_(2)O`

Answer

D

Explanation

In auto redox or disproportionation, same elements is oxidised as well as reduced. In (a) `Cl_(2)` (b) `H_(2)O_(2)` and (c ) `Cu^(+)` is oxidised as well as reduced. In (d) `N` is oxidised and `Cr` is reduced (in one mole of `(NH_(4))_(2)Cr_(2)O_(7)`)`and thus it is intramolecular redox.