Cartain materials such as turpentine oil, unsaturated organic compound, phosophorus, metals such as `Zn`, and `Pb`, etc., can absorb `O_(2)` from air in the presence of `H_(2)O`, which is converted to absorb `O_(2)` from air in the presence of `H_(2)O`, which is converted to `H_(2)O_(2)`. This is called autoxidation. Intermolecular redox reactions are those in which one molecule is oxidised and the other is reduced. Intramolecular redox reactions are those in which oen atom of a molecule is oxidised and the other atom is reduced.
Which of the following reactions is`//`are disproportionation reactions `(s)`?

Options

A. `Cl_(2)+2overset(ө)OHrarrCl^(ө)+ClO^(ө)+H_(2)O`
B. `2HCuCl_(2)rarrCu+Cu^(2+)4Cl^(ө)+2H^(o+)`
C. `HCHO+overset(ө)OHrarrCH_(3)OH+HCOO^(ө)`
D. `MgCO_(3)rarrMgO+CO_(2)`

Answer

A, B, C

Explanation

`{:(2e^(-)+Cl_(2) rarr2Cl^(ө)("Reduction")),(" "2ClO^(ө)+2e^(-) ("Oxidation")),(" "[Disproportionation]):}`

It is also a disproportional reaction.
`[overset(+1)Hoverset(+1)(Cu)overset(-1xx2)(Cl_(2))]`
`e^-)+Cu^(1+)rarrCu ("Reduction")`
`Cu^(1+)rarrCu^(2+)+e^(-)("oxidation")`
c. It is a also a disproportionation reduction. `HCHO` is oxidised to `HCOO^(ө)` and reduced to `CH_(3)OH`.
d. It is none since the oxidation state of `Mg` is `+2` in both reactant and product. Similarly, the oxidation states of `C` and `O` are `+4` and `-2` in both reactant and product.