why iron sulphide is a compound and not a mixture - Science - Is Matter Around Us Pure

Question

why iron sulphide is a compound and not a mixture?

Shalini Pandey · Accepted Answer

Iron Sulfide is a compound and not a mixture because when Iron
and Sulphur are mixed and heated then they combine chemically in
order to form a new substance named Iron Sulfide and after its
formation these can not be differentiated as individual elements
and in each portion of the Iron Sulfide the proportion of Iron and
Sulfur will be in same proportion