Answer :
Final answer:
The grain is the measurement used in the apothecary system for weight. It is a small unit equivalent to about 64.8 milligrams. Milligrams and grams, on the other hand, are metric units and not part of the apothecary system.
Explanation:
Apothecary System of Measurement
The apothecary system is an older system used primarily in the fields of medicine and pharmacy for measuring weight and volume. Among the various units of measurement in this system, the grain is a crucial unit for measuring weight. Specifically, one grain is equivalent to approximately 64.8 milligrams or 0.065 grams, making it a small unit often used for measuring the weight of medications and other substances.
Comparison with Other Measurements
In contrast, the milligram and gram are part of the metric system. While the milligram (mg) is a metric unit equal to one-thousandth of a gram, and the gram (g) is the base unit for mass in the metric system, they are not part of the apothecary system. Therefore, while both milligrams and grams are commonly used in scientific contexts, the correct answer regarding the apothecary system is the grain.
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