Final answer:
Sulfuric acid is used to increase zinc's solubility in a selective precipitation process, allowing for the separation of zinc from other substances like cadmium sulfide.
Step-by-step explanation:
The reason H₂SO₄ (sulfuric acid) is used to remove zinc is related to its ability to prevent the more soluble ZnS (zinc sulfide) from precipitating, allowing the less soluble CdS (cadmium sulfide) to precipitate out of the solution when saturated with H₂S (hydrogen sulfide). This process is typically aimed at the separation of metals by selective precipitation, which is not explicitly listed in the multiple-choice options provided by the student. However, of the choices given, the appropriate answer would seem to be C) To increase zinc's solubility, as sulfuric acid works to keep zinc in solution while allowing other substances, like cadmium sulfide, to precipitate out. The copper information provided does not aid in answering this question directly as it deals with the role of zinc in a redox reaction with copper, which is different from the selective precipitation process mentioned.