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# Elemental composition of pure substances

AP.Chem: SPQ‑2 (EU), SPQ‑2.A (LO), SPQ‑2.A.2 (EK), SPQ‑2.A.3 (EK)
You might need: Periodic table

## Problem

A 118, point, 0, space, g sample of a compound contains 72, point, 0, space, g of C, 18, point, 0, space, g of H, and 28, point, 0, space, g of N.
Which of the following is the empirical formula of the compound?