In the conductance of aqueous CuSO$_4$ solution, the current carriers are the

Analysis

The question asks for the identity of the particles responsible for carrying electric current through an aqueous solution of Copper(II) tetraoxosulphate(VI) ($CuSO_4$).

Concept Explanation

In chemistry, electrical conductivity is determined by the presence of mobile charge carriers.

1. In metals: Current is carried by delocalized electrons (mobile electrons).
2. In aqueous solutions (electrolytes): Current is carried by ions. When an ionic compound like $CuSO_4$ dissolves in water, it dissociates into its constituent ions: $$CuSO_4(aq) \rightarrow Cu^{2+}(aq) + SO_4^{2-}(aq)$$
3. Hydration: In an aqueous environment, these ions are surrounded by water molecules. This process is called hydration. The water molecules form a "shell" around the ions, making them hydrated ions. These hydrated ions are free to move toward the electrodes (cathode and anode) when a potential difference is applied, thereby conducting electricity.

Step-by-Step Solution

1. Identify the substance: $CuSO_4$ is an ionic salt.
2. Dissociation: Upon dissolving in water, it breaks into $Cu^{2+}$ and $SO_4^{2-}$ ions.
3. Interaction with solvent: Because the solvent is water, these ions become surrounded by water dipoles. They are no longer "naked" ions; they are hydrated ions.
4. Movement: Under the influence of an electric field, these hydrated ions migrate through the solution, acting as the charge carriers.
5. Evaluation of options: • A is incorrect because electrons carry current in wires/metals, not in aqueous solutions. • B is incomplete because it ignores the role of the solvent (water) in the solution phase. • C is correct because the ions are hydrated in the aqueous medium. • D is incorrect because "hydrated electrons" are specific, highly reactive species not involved in standard electrolytic conduction of salt solutions.

Conclusion

The current carriers in an aqueous solution of an electrolyte are the hydrated ions resulting from the dissociation of the solute.

Exam Tip: Always remember the rule: Metals conduct via electrons; Electrolytes (solutions/molten salts) conduct via ions. If the question specifies "aqueous," look for the option mentioning ions!