Question detail
What is the main reason that crude oil can be separated into different fractions?
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. Different fractions have different colours.
- B. Different fractions have different boiling points.
- C. All fractions have the same boiling point.
- D. Fractions are separated by their density only.
Answer
The correct option is Different fractions have different boiling points..
Explanation
The correct option is Different fractions have different boiling points.. Different fractions have different boiling points. is correct because it directly supports the approved learning objective to describe crude oil as a mixture of a very large number of compounds. 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
Misidentifying crude oil as a single compound
Students often think crude oil is a single, pure substance rather than a complex mixture of many hydrocarbons and other compounds.
Explain that crude oil is a heterogeneous mixture containing thousands of different molecules, mainly hydrocarbons, and that this diversity is why fractional distillation is needed to separate useful fractions.
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