AP Chemistrymediummcq1 pt
What is the mass percent of hydrogen in water (molar mass 18.02 g/mol)?
A.11.2%
B.5.6%
C.88.8%
D.16.0%
Explanation
Core Concept
Hydrogen contributes 2 × 1.008 = 2.016 g per mole. Percent = (2.016 ÷ 18.02) × 100% = 11.2%. Always divide the element's mass by the total formula mass.
Correct Answer
A11.2%
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