Which of the following is/are false?

Chemistry D and F - Block Elements General Single Correct MCQ

Published on: August 12, 2026

Na2Cr2O7 is used as a primary standard in volumetric analysis.

Potassium permanganate in excess on treatment with conc. H2SO4 forms manganese heptoxide

Phosphine, arsine and stibine all precipitates silver from silver nitrate

From kipp's apparatus waste ferric sulphate and ferrous sulphate mixture is obtained when air or oxygen is passed for longer time.

Text Solution

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The correct answer is:

Na2 Cr2O7 is not used as primary standard because it is hygroscopic in nature.

2KMnO4 + 3H2SO4 2KHSO4 + (MnO3)2SO4 + 2H2O

(MnO3)2SO4 + H2O Mn2O7 + H2SO4

PH3 + 6AgNO3 + 3H2O 6Ag + 6HNO3 + H3PO3

AsH3 + 6AgNO3 + 3H2O 6Ag + 6HNO3 + H3AsO3

3FeS2 + 2H2O + 11O2 2FeSO4 + Fe2(SO4)3 + 2H2SO4

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