Which statement concerning solutions is false?

• A. The solute is always a solid and the solvent is always a liquid.
• B. A solution is a homogeneous mixture of two or more substances.
• C. Solutions can exist in gaseous, liquid, or solid phases.
• D. The concentration of a solution can be expressed in molarity (mol/L).

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the definition of a solution. A solution is a homogeneous mixture of two or more substances, where the composition is uniform throughout.
2. Step 2: Recognize that solutions are not limited to just liquids; they can exist in all three phases: gaseous (e.g., air), liquid (e.g., saltwater), and solid (e.g., alloys).
3. Step 3: Know that the solute is the substance dissolved in the solvent, and the solvent is the medium that dissolves the solute. The solute and solvent can be solids, liquids, or gases depending on the solution.
4. Step 4: Understand concentration units such as molarity, which is defined as the number of moles of solute per liter of solution, expressed as \(M = \frac{\text{moles of solute}}{\text{liters of solution}}\).
5. Step 5: Evaluate the statements given and identify the false one by comparing it to the concepts above. The false statement is the one that incorrectly restricts the solute to always being a solid and the solvent to always being a liquid.