Question

Among $$PbS,CuS,HgS,MnS,Ag{}_{2}S,NiS,CoS,Bi{}_{2}S{}_3,\mathrm{\&}SnS{}_{2,}$$ 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 $$PbS,CuS,HgS,Ag{}_{2}S,NiS,CoS$$ compounds are all black in colour, where as $$MnS$$ is known to be dirty pink coloured, $$SnS{}_2$$ is yellow coloured compound, $$Bi{}_{2}S{}_3$$ 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.
$$Ag{}_{2}S$$ 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 $$Bi{}_{2}S{}_3$$ as a black coloured sulphide compound. Just remember that it is a brownish black crystalline compound which when precipitated gives black colour.