Which of the following is the atomic mass of potassium (K)?

• A. 22.99 u
• B. 35.45 u
• C. 40.08 u
• D. 39.10 u

Answer: (D)

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 (u).
2. Recognize that the atomic mass listed on the periodic table for potassium (K) is approximately 39.10 u, which reflects this weighted average.
3. Compare the given options to known atomic masses of elements: 22.99 u corresponds to sodium (Na), 35.45 u corresponds to chlorine (Cl), and 40.08 u corresponds to calcium (Ca).
4. Identify that none of the provided options exactly match the known atomic mass of potassium, which is about 39.10 u, indicating the correct atomic mass is not listed among the options.
5. Conclude that the correct atomic mass of potassium is approximately 39.10 u, based on standard periodic table data.