Question

The incorrect statement out of the following is ____
A. Ferric ion gives blood red colour with potassium thiocyanate
B. $$Cu^{2 +} $$ salts give red coloured borax bead test in reducing flame.
C. $$Cu^{2 +} $$ ion gives chocolate coloured precipitate with potassium ferrocyanide solution
D. $$Cu^{2 +} $$ and $$N{i^{2 + }}$$ ions give black precipitate with $H_2S$ In presence of HCl solution

Answer 1

Hint: The bead test is a traditional part of qualitative inorganic analysis to test for the presence of certain metals. The oldest one is the borax bead test or blister test. It was introduced by Berzelius in $$1812.$$ Since then other salts were used as fluxing agents, such as sodium carbonate or sodium fluoride.

Complete step by step answer:
The incorrect statement out of the following is $$Cu^{2 +} $$ salts give red coloured borax bead test in reducing flame. Due to the common ion effect, sufficient $${S^{2 - }}\;$$ concentration does not produce and not form ppt of NiS. The bead test, sometimes called the borax bead or blister test, is an analytical method used to test for the presence of certain metals. The premise of the test is that oxides of these metals produce characteristic colors when exposed to a burner flame. The test is sometimes used to identify the metals in minerals. Sodium ions are not coloured. Therefore, they do not give a borax bead test. This test is given by coloured salts.

Hence correct option is (B)

Note: a borax bead test is A chemical test to disclose the presence of certain metals in a sample. A clear glassy bead of borax fused in a wire loop will react chemically with the salts of certain metals and yield colors that help to identify the metal