Final answer:
MgCl2 and Na2O are the compounds that will conduct electricity when dissolved in water because they dissociate into ions, which are necessary for electrical conductivity.
Step-by-step explanation:
The student is asking about the electrical conductivity of aqueous solutions of different compounds. The ability of a solution to conduct electricity depends on the presence of mobile ions. When ionic compounds dissolve in water, they dissociate into ions that allow electric current to flow. Among the compounds listed — MgCl2, Na2O, C12H22O11, and C2H5OH — the two that will conduct electricity when dissolved in water are MgCl2 and Na2O.
MgCl2 is an ionic compound composed of Mg2+ and Cl− ions. When dissolved, it disassociates and becomes a good conductor of electricity due to the movement of these ions. Similarly, Na2O will react with water to form Na+ and OH− ions, thus also conducting electricity.
In contrast, C12H22O11 (sucrose) and C2H5OH (ethanol) do not dissociate into ions. Sucrose is a sugar molecule that remains non-ionic in solution, and ethanol, while a polar molecule, does not produce ions in solution either. Therefore, these compounds are nonelectrolytes and do not conduct electricity.