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Calculate the mass percentage of carbon in methane, CH4. (Atomic masses: C = 12, H = 1)
A25 %
B50 %
C75 %
D80 %
Answer & Solution
Correct answer: C. 75 %
1. Molecular mass of CH4 $= 12 + (1 \times 4) = 16$ g.
2. Mass % of C $= \dfrac{12}{16} \times 100$.
3. $= 75\%$.
The value $25\%$ is the percentage of hydrogen, not carbon.
_Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit 7 Atoms and Molecules "Percent Composition", p.105_
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