Redox reactions involve simultaneous reduction-oxidation reactions. The process of oxidation involves addition of oxygen or any other electronegative element or loss of hydrogen or any other electropositive element. The reverse of this process is called reduction. Reduction also involves addition of electrons or decrease in the oxidation number an atom or ion present in a substance. Substances which bring about oxidation of other substances are called oxidants while those which bring about the reduction of other substances are called reductants. In terms of electronic concept, reductants. In terms of electronic concept, reductants are electron donors while oxidants are electron acceptors. Oxidants also involve decrease in oxidation number of one of its atoms/ions while reductants involve increase in the oxidation number of one of its atoms/ions.
Oxidation numbers are always while numbers and must be always calculated on the basis of their structures and never from their molecular formulae. Redox reactants may involve combination of atoms/molecules, decomposition of substances, displacement of metals of non metals and disproportionation of a particular species which may be metals, non-metals or ions. Redox reactions can be balanced both by oxidation number method as well as by ion electron method.
Amongst the following, identify the species with an atom in +6 oxidation state

Options

A. `MnO_(6)^(-)`
B. `Cr(CN)_(6)^(3-)`
C. `MnF_(6)^(2-)`
D. `CrO_(2)Cl_(2)`

Answer

D

Explanation

O.N. of Cr in `CrO_(2)Cl_(2)` (chromyl chloride) = x (say)
`:. x +2(-2) +2(-1)=0`
`rArr x = +6`.