Question

Select the incorrect statement(s) :

A. In K₂MnO₄ and CrO₂Cl₂, The central transition metals/ions have the same oxidation state.
B. Both sodium and potassium dichromate can be used as primary standard in volumetric estimations.
C. Potassium dichromate on strong heating evolves oxygen gas and forms green powder.
D. Potassium permangnate on heating with solid KOH evolves oxygen gas and forms a black powder.

Answer 1

The incorrect statements are that K₂MnO₄ and CrO₂Cl₂ have the same oxidation state for their central metals. The correct statement(s) among the given options are A and C.

Step-by-step explanation:

The statement 'In K₂MnO₄ and CrO₂Cl₂, The central transition metals/ions have the same oxidation state' is incorrect. In K₂MnO₄, manganese has an oxidation state of +6, while in CrO₂Cl₂, chromium has an oxidation state of +4. Moving on to the next statement.

'Both sodium and potassium dichromate can be used as primary standard in volumetric estimations', this is also incorrect because sodium dichromate is hygroscopic and is not used as a primary standard. Potassium dichromate is used as a primary standard due to its stability and non-hygroscopic nature.

Concerning the statement 'Potassium dichromate on strong heating evolves oxygen gas and forms green powder', this is correct. Lastly, 'Potassium permanganate on heating with solid KOH evolves oxygen gas and forms a black powder' is correct.