Question

This sulphide is not black:

• A. PbS
• B. NiS
• C. MnS
• D. CoS

Hint:

Manganese sulfide ($MnS$) is highly unique in qualitative analysis due to its distinct flesh-pink color, making it easy to differentiate from the common black transition metal sulfides.

Answer 1

The Correct Option is C

Step 1: Why colour matters here.
In salt analysis we precipitate metals as sulphides, and the colour of each sulphide helps us name the metal.

Step 2: Recall the usual black sulphides.
Lead, nickel and cobalt all give dark black sulphide precipitates. So $PbS$, $NiS$ and $CoS$ are black.

Step 3: Recall the special one.
Manganese sulphide is the exception. $MnS$ comes down as a light flesh or buff coloured solid, not black.

Step 4: Choose the one that is not black.
Three are black and only manganese sulphide is pale, so that is the answer.
\[ \boxed{MnS} \]