Question detail

What is the relative formula mass (Mr) of propane (C₃H₈)?

Try the question, check the answer, then read the explanation to understand the curriculum point.

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At a glance

MCQ

Type

practice

Style

Topic

Carbon compounds as fuels and feedstock

Question

A. 44.1 g/mol
B. 44.0 g/mol
C. 44.2 g/mol
D. 44.3 g/mol

Answer

The correct option is 44.0 g/mol.

Explanation

The correct option is 44.0 g/mol. 44.0 g/mol is correct because it directly supports the approved learning objective to represent alkane molecules in displayed, structural and molecular formula forms. This belongs to Crude oil, hydrocarbons and alkanes within Carbon compounds as fuels and feedstock, so the answer must use the correct organic chemistry context. The other options are incorrect when they confuse the organic family, formula type, reaction condition, product, or property being tested. Keep molecular formula, structural formula, displayed formula, and general formula distinct. Do not confuse alkanes with alkenes, saturated with unsaturated, cracking with combustion, polymers with monomers, or hydrocarbons with oxygen-containing alcohols and carboxylic acids. When formulae are used, preserve the stored notation exactly and explain the GCSE chemistry idea in words rather than using unsupported displayed-formula diagrams.

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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