What is the percent by mass of oxygen in carbon dioxide open paren cap c cap o sub 2 close paren ? Use percent Element is equal to total mass of element in compound over molar mass of compound times 100

Carbon dioxide (CO₂) contains two oxygen atoms, so the oxygen contributes 2 × 16.00 = 32.00 g/mol. The molar mass of CO₂ is 12.01 + 32.00 = 44.01 g/mol. Thus, the percent by mass of oxygen is (32.00 ÷ 44.01) × 100 ≈ 72.71%, so the correct choice is 72.71 percent.

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