Which of the following is closest to the atomic mass of krypton (Kr)?

• A. 39.10 u
• B. 20.18 u
• C. 83.80 u
• D. 131.29 u

Answer: (C)

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. Recall that krypton (Kr) is a noble gas with several isotopes, and its atomic mass is typically around the mid-80s in atomic mass units.
3. Compare the given options to typical atomic masses of elements: 39.10 u is close to potassium, 20.18 u is close to neon, 131.29 u is close to xenon, and 83.80 u is close to krypton.
4. Use the periodic table or reliable reference to confirm that krypton's atomic mass is approximately 83.80 u.
5. Select the option 83.80 u as the closest atomic mass to krypton.