Here's why:

* Reactants: FeS (iron(II) sulfide) and 2HCl (hydrochloric acid)

* Products: FeCl₂ (iron(II) chloride) and H₂S (hydrogen sulfide)

Explanation:

In this reaction, the more reactive metal (iron, Fe) in FeS displaces the less reactive hydrogen (H) from HCl. The iron combines with chlorine (Cl) to form iron(II) chloride (FeCl₂), while the hydrogen combines with sulfur (S) to form hydrogen sulfide (H₂S).

General form of a single displacement reaction:

A + BC → AC + B

where:

* A is a more reactive element

* B is a less reactive element

* C is an element or group of elements

Let me know if you'd like to see more examples or have any other chemistry questions!