Which instrument is used to make solutions of known concentration and provides accurate liquid volume measurement?

• A. Volumetric Flask
• B. Graduated Cylinder
• C. Thermometer
• D. Beaker

Answer: (A)

The ability to prepare solutions with a precise, known concentration depends on having a container that gives an exact final volume. A volumetric flask is designed for this purpose. It has a long neck with a single calibration mark and is manufactured so that when filled to that mark, it contains exactly the stated volume (at the specified temperature, usually 20°C). This allows you to dissolve the solute and fill with solvent up to the mark, giving a final volume you know precisely. With that exact volume, the concentration is determined by the amount of solute divided by the precise final volume. Other lab glassware either provides approximate volumes (like a graduated cylinder) or is intended for mixing and general handling rather than accurate final volumes (like a beaker), and a thermometer measures temperature, not volume.