Water dissolves polar and ionic compounds easily. Which option correctly names the compounds that dissolve easily due to water's polarity?

• A. Polar covalent molecules
• B. Polar and ionic compounds
• C. Nonpolar molecules
• D. Metallic compounds

Answer: (B)

Water’s polarity means its molecules have partial charges that can interact with charged or highly polar solutes. Ionic compounds dissociate into ions, and water stabilizes those ions by forming hydration shells around them, which lowers the energy barrier to dissolve and often overcomes the lattice energy holding the solid together. Polar covalent molecules also dissolve well when they have a permanent dipole that can align with water’s dipole and form hydrogen bonds or dipole–dipole interactions with water, allowing the solute to be solvated. Nonpolar molecules, lacking a dipole, don’t interact strongly with water’s charged regions and hence don’t dissolve as readily. Metallic compounds aren’t dissolved by water in the same way; they’re not solvated like ions or polar molecules. So the substances that dissolve easily because of water’s polarity are polar and ionic compounds.