Oxidation is de-electronation whereas reduction is electronation and both occur simultaneously. The overall chemical change is called redox reaction. Redox reactions are of three types: (i) Intermolecular redox reactions, (ii) Autoredox or disproportionation reaction, and (iii) Intramolecular redox reactions. Oxidants are themselves reduced and oxidise reductants. The oxidation number of an element in acompound decides its nature to act as oxidant or reductant.
Which of the following show intramolecular redox change:
`(I) 2KCIO_3 to 2KCl +3O_2`
`(II) (NH_4)_2 Cr_2 O_7 toN_2 +Cr_2 O_3 + 4H_2 O`
`(III) NH_4 NO_2 toN_2 + 2HO_2 O`
`(IV) 2Cu^(2+) toCu^(2+) + Cu`

Options

A. II,III
B. I,IV
C. I,II,III
D. II,IV

Answer

C

Explanation

It involves redox change of two species in a molecule.