The first question is always a simple question about electron structure, they're not usually worth much marks, but if you don't know it, of might be a good idea to learn it.
I also don't really think you should waste time trying to predict what will come up, but I do think that the 6 market won't be an evaluate/compare question, since we've had 2 of them in the last 3 years. It is more likely to be fractional distillation of crude oil, but it could always be something like the evolution of the atmosphere. So what I'm saying really is try to revise/learn everything on the specification.