Which instrument is best for measuring the volume of a liquid?

• A. Graduated cylinder
• B. Ruler
• C. Beaker
• D. Thermometer

Answer: (A)

Measuring how much liquid is in a container is about reading a precise volume, not just holding the liquid. A graduated cylinder is designed for that purpose: it has finely marked volume intervals along a narrow, tall shape that minimizes error and lets you read the liquid level accurately. To get the correct reading, you look at the bottom of the meniscus at eye level and use the smallest division available.

Rulers measure length, which isn’t useful for volume. Beakers can hold liquids and have volume marks, but their wide shape and larger spacing between marks make them far less precise for small amounts. Thermometers measure temperature, not how much liquid there is.

So the graduated cylinder provides the most accurate measurement of liquid volume.