Final answer:
In an aqueous solution, HCOOH (formic acid) ionizes to produce formate ions (HCOO-) and hydrogen ions (H+).
Step-by-step explanation:
The solute particles present in an aqueous solution of HCOOH, which is formic acid, are formate ions and hydrogen ions. When formic acid dissolves in water, it partially ionizes to produce H+ and HCOO-ions. This is a characteristic behavior of acids in aqueous solutions, where they donate a proton (H+) to water, leaving behind the corresponding anion. Therefore, the correct answer to the question is c) Formate ions and d) Hydrogen ions.