Select the incorrect statement(s) :

Chemistry D and F - Block Elements General Single Correct MCQ

Published by: CGP EDU Academic Team

Published on: August 11, 2026

In K 2 MnO 4 and CrO 2 Cl 2 , the central transition metals/ions have same oxidation state.

Both sodium and potassium dichromate can be used as primary standard in volumetric estimations.

Potassium dichromate on strong heating evolves oxygen gas and forms green powder.

Potassium permanganate on heating with solid KOH evolves oxygen gas and forms a black powder.

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(b,d)

In both compounds central metals have + 6 oxidation states.

MnO 4 2– ; x + 4 (– 2) = – 2, So, x = 6. ;

CrO 2 Cl 2 ; x + 2 (– 2) + 2 (–1) = 0, So, x = 6.

Sodium dichromate is Na 2 Cr 2 O 7 .2H 2 O, so it can not be weighed correctly for the preparation of standard solution.

2K 2 Cr 2 O 7 2K 2 CrO 4 + Cr 2 O 3 (green) + 3/2 O 2 .

4KMnO 4 + 4KOH 4K 2 MnO 4 (green) + 2H 2 O + O 2

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