The relative atomic mass of an element is
Correct answer: B. the average mass of its atoms compared with one twelfth the mass of a carbon 12 atom
- A. the mass in grams of one atom of the element
- B. the average mass of its atoms compared with one twelfth the mass of a carbon 12 atom
- C. the number of protons in its nucleus
- D. always a whole number
Explanation
Relative atomic mass is a ratio, so it has no units, and it is an average weighted by the natural abundance of the isotopes. That averaging is why chlorine is quoted as 35.5 rather than as a whole number, since it is a mixture of chlorine 35 and chlorine 37. The number of protons is the atomic number, an entirely different quantity.
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About Moles and Avogadro's Number
The mole connects the microscopic number of particles with measurable mass, using Avogadro's number, 6.022 × 10²³ particles per mole. Questions involve molar mass, conversion between mass, moles and particles, percentage composition, empirical and molecular formulas, and distinguishing atoms, molecules, ions and formula units.
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