Which laboratory instrument would you use to measure the mass of a substance?

The laboratory balance is the appropriate instrument for measuring the mass of a substance because it is specifically designed to provide accurate measurements of weight. Laboratory balances come in various types, such as analytical and top-loading balances, each suitable for different levels of precision and types of samples. These instruments utilize a scale to quantify mass based on the gravitational pull acting on the object being weighed, allowing for precise mass measurements that are essential in many scientific applications.

In contrast, graduated cylinders are intended for measuring the volume of liquids, micropipets are designed for transferring small volumes of liquid with precision, and medicine droppers are typically used for dispensing specific amounts of liquid, but none of these serve to measure mass directly. Thus, when it comes to obtaining a measurement of mass in a laboratory, the laboratory balance is the correct choice.