C4 C5 C6 are definitely the heaviest chemistry topics (closely followed by C7). There is just so much information, formulae, equations etc. to remember, yet in the exam, only a quarter of what we studied will appear (which I find really annoying although I know they can't include everything).
This is the paper I am most worried about because I don't remember learning C5 or C6 (school's fault for not teaching well & my fault for being ill).
This weekend is going to be intense chemistry and a little physics revision for me! Fun