Lesson: Chapter 7 — Quantification of Elements and Compounds

7.1. Relative atomic mass 11 of 12 Reset answers

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Question 11

The mass of a sodium atom is 3.819 × 10^-23 g. The value of the atomic mass unit is 1.67 × 10^-24 g. What is the relative atomic mass of sodium?

A 0.04 B 276 C 1.92 D 23

The right answer is the one marked above.

23. A_r = (3.819 × 10^-23 g) ÷ (1.67 × 10^-24 g) = 23.

No division by 12 was needed here — the value of the unit was given already. Dividing by 1.99 × 10^-23 g instead gives 1.92.

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