# Chapter 2 Atoms, Molecules, and Ions - Study Questions - Page 95i: 140

D

#### Work Step by Step

Atomic weights (g/mol): $C: 12.011, \ H: 1.008$ Molar mass of $C_8H_{18}$: $114.23\ g/mol$ In 57.1 g: $57.1\div 114.23=0.500\ mol$ A is correct Mass fraction of C: $8\times12.011\div114.23\times100\%=84.12\%$ B is correct Empirical formula: $C_4H_9$ (Maximum common divisor of 8 and 18 is 2) C is correct Mass fraction of H: $15.88\%$ D is incorrect

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