Question detail
Why do fractions obtained from fractional distillation of crude oil contain hydrocarbons with similar chain lengths?
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. Because the crude oil is initially a pure substance with only one chain length.
- B. Because the distillation column is designed to separate compounds by their mass only.
- C. Because compounds with similar chain lengths have similar densities and therefore separate by gravity.
- D. Because compounds with similar chain lengths have similar boiling points and therefore separate by temperature.
Answer
The correct option is Because compounds with similar chain lengths have similar boiling points and therefore separate by temperature..
Explanation
The correct option is Because compounds with similar chain lengths have similar boiling points and therefore separate by temperature.. Because compounds with similar chain lengths have similar boiling points and therefore separate by temperature. is correct because it directly supports the approved learning objective to explain that each fraction contains molecules with a similar number of carbon atoms. This belongs to Fractional distillation and petrochemicals 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
Misunderstanding Fraction Composition
Students often think that each fraction from fractional distillation contains only one type of hydrocarbon.
Clarify that each fraction actually contains a mixture of hydrocarbons with a similar number of carbon atoms.
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