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WBCS Main Examination 2023 — Paper IV: General Studies II · Question 71 of 200

Q71
General ScienceChemistry
The colour of CuS is
  1. a.Black
  2. b.Blue
  3. c.Yellow
  4. d.Red

Answer: (A) Black

Copper(II) sulphide precipitates as a black solid when H$_2$S is passed through a copper salt solution, a standard test in group II analysis. Blue is the colour of hydrated copper sulphate (CuSO$_4$), and yellow sulphides are those of cadmium or arsenic.

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The colour of CuS is — WBCS Main Examination 2023 Q71 | Prostuti360°