In a disproportionation reaction, the disproportionate substance
has exactly one oxidation state.
has exactly two oxidation states.
has at least three oxidation states.
has either one or two oxidation states.

The correct statement is has at least three oxidation states.

Explanation:

Disproportionation reaction is defined as the chemical reaction in which a single substance gets reduced as well as oxidized.

For a substance to get disproportionate, it should contain at least three oxidation states.

For Example: The reaction of chlorine with water follows the equation:

Here, chlorine gas is getting reduced from to HCl. The oxidation state of chlorine is reducing from 0 to -1.

Chlorine is also getting oxidized from to HClO. The oxidation state of chlorine is getting increases from 0 to +1.

Hence, the number of oxidation state of chlorine are 0, -1 and +1.

Thus, the correct statement is has at least three oxidation states.

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