Hydrated Substances Defined

Steps:

• Recall that a hydrated substance involves water molecules incorporated into a compound's structure.
• Examine each option for accuracy against the standard chemical definition.
• Eliminate options that misrepresent solubility, composition, or chemical bonding.
• Select the option that precisely describes chemical combination with water.

Why D is correct:

• Hydrated substances, like CuSO₄·5H₂O, have water molecules chemically bound in the crystal lattice, forming a distinct compound.

Why the others are wrong:

• A: Barium sulfate is insoluble, not a defining trait of hydration.
• B: Hydration applies to both ionic and covalent compounds, not just ionic ones.
• C: Hydrogen alone does not define hydration; it's specifically water (H₂O).

Final answer: D