Chemistrymedium · Past Paper
What is the percentage of Oxygen in Calcium Carbonate ($CaCO_3$)? (Ca=40, C=12, O=16)
A16%
B32%
C48%
D60%
✓ Correct Answer: C — 48%
Total mass = 100. Mass of Oxygen = 3 * 16 = 48. % of O = (48/100) * 100 = 48%.
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