Final answer:
The mass of aluminum in amu for a sample of 75 atoms is calculated by multiplying the number of atoms by the atomic mass of aluminum, providing a result of 2025 amu.
Step-by-step explanation:
The question asks us to calculate the mass of aluminum in amu for a sample that contains 75 arm. However, there seems to be a misunderstanding, as 'arm' is not a standard unit of measurement in chemistry. Assuming the question is asking for the mass in atomic mass units (amu) of aluminum atoms, we can use the relative atomic mass of aluminum, which is approximately 27 amu per atom.
If we are considering 75 atoms of aluminum (since 'arm' is perhaps a typo for 'atoms'), the mass would be:
Mass of 75 Al atoms = 75 atoms × 27 amu/atom = 2025 amu
This calculation assumes each aluminum atom has an atomic mass of approximately 27 amu, which is standard for aluminum.