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Testing for an alkene
Propene (C₃H₆) is an alkene.
Describe the test for alkenes. Give the result.
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Marking points
- 1 Test: add bromine water.
- 2 Result: bromine water changes from orange to colourless or decolourises, conditional on the correct test.
Full-mark answer
Test: add bromine water. Result: the bromine water changes from orange to colourless (it is decolourised).
Why this answer loses marks
The bromine water goes clear.
The official mark scheme ignores “clear”; describe the bromine water as becoming colourless or decolourising.