JEE Main On 16 April 2018 Question 22

Question: The incorrect statement out of the following is ______________.

Options:

A) A Ferric ion gives blood red colour with potassium thirocyanate

B) $ c{u^{2+}} $ salts give red coloured borax bead test in reducing flame.

C) $ c{u^{2+}} $ ion gives chocolate coloured precipitate with potassium ferrocyanide solution

D) $ C{u^{2+}} $ and $ N{i^{2+}} $ ions give black precipitate with in presence of solution

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Answer:

Correct Answer: C

Solution:

  • $ C{u^{2+}} $ ion does not give chocolate coloured precipitate with potassium ferrocyanide solution instead it forms white precipitate. The reaction can be as follow: $ K _4[Fe(CN _6)+2CuSO _4\to [Fe(CN _6)]+2K _2SO _4] $