Final answer:
The atomic mass of an element is crucial for chemists to identify the element, determining substance composition, and calculating the number of atoms or molecules in a sample.
Step-by-step explanation:
In the early 1880s, the British Scientist John Dalton worked to find the atomic mass of several common elements. Knowing the atomic mass of an element helps a chemist in several ways. One major way is that the atomic mass could be used to identify an element (option B). Atomic mass aids in determining the elemental composition of substances and plays a crucial role when calculating the molar mass of compounds. It allows chemists to quantitatively describe the composition of substances by summing the average atomic masses of all the atoms represented in a substance's formula. Moreover, atomic mass is critical for chemists to know how many atoms or molecules are contained in a measurable amount of sample. It's worth noting that Dalton's focus on quantitative measurement led to his atomic theory, which explained that elements combine in fixed ratios of mass, supporting the law of definite proportions.