Question detail
What percentage of the mass of ethane (C₂H₆) is due to hydrogen atoms?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Carbon compounds as fuels and feedstock
Question
- A. 27.5 %
- B. 25.0 %
- C. 30.0 %
- D. 32.5 %
Answer
The correct option is 27.5 %.
Explanation
The correct option is "27.5 %" because it supports the approved learning objective: Represent alkane molecules in displayed, structural and molecular formula forms. The other options are incorrect or weaker because they are vague, use the wrong Chemistry context, or do not clearly explain the answer for Crude oil, hydrocarbons and alkanes.
Common mistake
Mislabeling displayed formula as molecular formula
Students often write the same line‑bond diagram (displayed formula) and then state it as the molecular formula, forgetting that the molecular formula is a concise representation of the element counts, e.g. C₄H₁₀ for butane.
Explain that the displayed formula shows the connectivity of atoms, while the molecular formula lists the number of each element in the molecule. For butane, the displayed formula is CH₃–CH₂–CH₂–CH₃, the structural formula is the same with explicit bonds, and the molecular formula is C₄H₁₀.
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