What is the name of the gas liberated when diluted hydrochloric acid is added to iron(ii)sulphide?

A. turns lime water milky
B. decolorizes bromine water
C. gives a pop sound
D. turns lead(ii)ethanoate paper black

Correct Answer:

Option D – turns lead(ii)ethanoate paper black

Explanation

– Iron sulfide reacts with hydrochloric acid, releasing hydrogen sulfide: FeS + 2HCl → FeCl₂ + H₂S.

– Hydrogen sulfide reacts with lead acetate to form lead sulfide and thus produces a coloration on the paper which will vary from yellow to black, depending upon the amount of hydrogen sulfide present.