The atomic mass of the element niobium (Nb) is 92.906 amu. Which of the following measurements correctly represents this atomic mass?

• A. 92.906 amu
• B. 92.9 amu
• C. 92.906 g
• D. 93 amu

Answer: (A)

Verified step by step guidance

1. Understand that atomic mass is typically expressed in atomic mass units (amu), which is a unit specifically designed to express the mass of atoms and molecules.
2. Recognize that the atomic mass given, 92.906 amu, is a precise measurement that includes decimal places to reflect the weighted average of all isotopes of niobium.
3. Evaluate each option to see if it correctly represents the atomic mass: it must have the correct unit (amu) and the correct level of precision.
4. Note that '92.9 amu' is rounded and less precise, '92.906 g' uses the wrong unit (grams instead of amu), and '93 amu' is rounded and less precise.
5. Conclude that the measurement '92.906 amu' correctly represents the atomic mass because it has the correct unit and the appropriate precision.