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Crude oil is separated into petrol, diesel and tar by careful heating. Which property makes this possible?
ATheir densities all differ
BTheir boiling points differ
CTheir colours all differ
DTheir smells all differ
Answer & Solution
Correct answer: B. Their boiling points differ
1. Crude oil is a mixture of many different substances.
2. Each of those substances boils at its own temperature.
3. Heating the mixture slowly makes the lowest boiling substance evaporate first.
4. Raising the temperature further drives off the next one, and so on.
5. Separating a mixture this way is called fractional distillation.
6. Colour and smell can be noticed but cannot be used to split the mixture apart.
_Source: Siyavula Natural Sciences Grade 7 (CC BY 4.0), Formation of crude oil and natural gas_