In an analytical balance, what part is referred to as the support for the arms?

The correct answer is the beam. In an analytical balance, the beam serves as the support for the arms, which are attached to it and hold the weighing pan. The beam is integral to the balance's operation as it facilitates the precise measurement of mass by comparing the weight of the sample on the pan to reference weights.

In analytical balances, maintaining a stable and level beam is crucial for accurate measurements. The design allows for an even distribution of weight, ensuring that any changes in mass can be detected accurately. Understanding the function of the beam helps clarify how analytical balances achieve their high degree of precision in weighing substances.