Which term describes the average weight of all naturally occurring forms of the element?

• A. Atomic Weight
• B. Density
• C. Solution
• D. Solute

Answer: (A)

The main idea here is how an element’s mass is represented when it occurs in nature with different isotopes. Each isotope has its own mass, and those isotopes appear in particular natural abundances. To get the average mass you'd expect to measure from a large sample of the element as it occurs naturally, you take a weighted average that accounts for how common each isotope is. That weighted average is called the atomic weight. It’s typically expressed in atomic mass units and often isn’t a whole number because of the varying abundances of isotopes on Earth. The other terms describe different concepts: density is mass per volume, a solution is a mixture where a solute is dissolved in a solvent, and a solute is the substance being dissolved.