Lesson: Chapter 7 — Quantification of Elements and Compounds

7.2. Relative molecular mass 3 of 10 Reset answers

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Question 3

What is the relative molecular mass of ammonia (NH₃)? (A_r: H = 1, N = 14)

A 17 B 16 C 15 D 43

The right answer is the one marked above.

17. NH₃ = 14 + (3 × 1) = 17.

15 comes from ignoring the subscript 3 and taking 14 + 1. 43 comes from multiplying the nitrogen by three instead of the hydrogen.

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