A student in Trinidad tested four colourless liquids labelled P, Q, R and S. Liquid P decolourized bromine water. Liquid Q turned blue litmus paper red and produced carbon dioxide with sodium carbonate. Liquid R produced a brick-red precipitate with Fehling's solution. Liquid S turned acidified potassium dichromate from orange to green. Which liquid is an alkene?

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Question

A student in Trinidad tested four colourless liquids labelled P, Q, R and S. Liquid P decolourized bromine water. Liquid Q turned blue litmus paper red and produced carbon dioxide with sodium carbonate. Liquid R produced a brick-red precipitate with Fehling's solution. Liquid S turned acidified potassium dichromate from orange to green. Which liquid is an alkene?

Accepted Answer

P — Award 1 mark for A. Liquid P decolourized bromine water, which is the characteristic test for alkenes (unsaturated hydrocarbons containing C=C double bonds). B is incorrect — Q shows properties of a carboxylic acid. C is incorrect — R shows properties of an aldehyde or reducing sugar. D is incorrect — S shows properties of an alcohol.

Answer

S

Answer

R

Answer

Q

Answer

P

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