Question

Among \[PbS,CuS,HgS,MnS,Ag{}_2S,NiS,CoS,Bi{}_2S{}_3,\& SnS{}_{2,}\] the total number of black coloured sulphide are:
a) \[6\]
b)\[7\]
c) \[8\]
d) \[9\]

Answer 1

Hint: Just having the basic knowledge of the compounds is enough to know get the correct answer to this question. They are a certain colour because they are found in nature or they are naturally occurring like that.

Complete step by step answer:
As its very distinct that \[PbS,CuS,HgS,Ag{}_2S,NiS,CoS\] compounds are all black in colour, where as \[MnS\] is known to be dirty pink coloured, \[SnS{}_2\] is yellow coloured compound, \[Bi{}_2S{}_3\] is a brownish black coloured compound so the correct answer is; option A.
There are total \[6\] black coloured sulphide compounds.
Additional information: \[PbS\] or phosphate buffered saline is a buffer solution which is commonly used in biological research. It is a water based salt solution which contains sodium hydrogen phosphate. The buffer helps to maintain the pH.
\[CuS\] Or copper monosulfide is a chemical compound of copper and sulphur. It has a moderate conductor of electricity. It has a potential use in catalysis.
\[HgS\]Or mercury sulphide is a chemical compound composed of elements like mercury and sulphur. It is insoluble in water.
\[Ag{}_2S\] Or silver sulphide is an inorganic compound which is a dense black solid which is the only sulphide of silver. It has many uses like a photosensitizer in photography. It is insoluble in solvents and can be degraded by strong acids.
\[NiS\] Or nickel sulphide is also an inorganic compound which is black solid which can be produced by treating nickel salts with hydrogen sulphide. They are sometimes used as catalysts.
\[CoS\] Or carbonyl sulphide is a colourless, flammable gas with a very unpleasant odor.

So, the correct answer is Option A.

Note: This is a tricky question as some of you might consider \[Bi{}_2S{}_3\] as a black coloured sulphide compound. Just remember that it is a brownish black crystalline compound which when precipitated gives black colour.