Which of the following is the atomic mass of arsenic (As)?

• A. 79.90
• B. 74.92
• C. 74.92
• D. 32.07

Answer: (B)

Verified step by step guidance

1. Understand that the atomic mass of an element is the weighted average mass of all its naturally occurring isotopes, measured in atomic mass units (amu).
2. Locate arsenic (As) on the periodic table to find its atomic mass, which is usually listed below the element symbol.
3. Recall that the atomic number of arsenic is 33, but this is not the atomic mass; the atomic mass is a decimal value close to the mass number of its most common isotopes.
4. Compare the given options (79.90, 74.92, 32.07) with the typical atomic mass of arsenic found on the periodic table, which is approximately 74.92 amu.
5. Conclude that the correct atomic mass of arsenic is 74.92 amu, as it matches the standard value from the periodic table.