Poly(tetrafluoroethene) (PTFE) is a polymer made from tetrafluoroethene.
Figure 1 shows a molecule of tetrafluoroethene.

On Figure 1, draw a circle around the functional group that allows this molecule to undergo addition polymerisation.
Practise Edexcel GCSE Chemistry Polymers with exam-style questions for Foundation and Higher tier. 100 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.