Question Constellation Sign up for free AQA · GCSE · Chemistry · Higher
Formation of crude oil
Some fractions of crude oil are processed to produce fuel for transport.
Describe how crude oil was formed.
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Marking points
- 1 Identifies dead plankton or ancient biomass as the starting material.
- 2 States that the remains were buried in mud or sediment.
- 3 States that the remains were compressed.
- 4 Gives the timescale as millions of years.
Full-mark answer
Crude oil formed from dead plankton or other ancient biomass that was buried by mud and sediment. The buried remains were compressed and changed into crude oil over millions of years.
Why this answer loses marks
Crude oil formed from dead organisms underground.
This is too vague to earn the full marks because it omits burial by sediment, compression and the long timescale.