Which instrument is typically read with two decimal places of precision?

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

Answer: (B)

The capacity to read two decimal places comes from the instrument having many fine markings along its length, which allows you to estimate the level of liquid beyond the smallest division. Beakers and Erlenmeyer flasks have coarse, widely spaced marks and are meant for approximate volumes, so the readings are reported only to the nearest milliliter or so. A volumetric flask is calibrated for a single, exact volume and is filled to a mark, not read across many divisions. A graduated cylinder, in contrast, is designed with multiple precise graduations, enabling you to read the liquid level to a small increment and estimate the last digit. By looking at the bottom of the meniscus at eye level and interpolating to the hundredths place, you can report volumes like 25.42 mL. That combination of fine scale and interpolation is why the graduated cylinder is typically read with two decimal places of precision.