Chemistry Test in 2 days...What do I do?

Basically in my December mock exams I didn't do to great and I achieved a 4 however I didn't revise for the exam as I was revising more for Physics and Biology. Also I didn't understand chemistry then but suddenly I'm starting to get it. As I got 4 in my exam I was told by my teacher that I'll be doing the foundation test however I believe I can achieve at least a 6 in chemistry so I want to do other higher paper as the maximum grade you can get for foundation is 5.

My teacher told me to come after school on Wednesday for a test and to prove that I able to the higher paper. That's in two days so what do I do? What is the best way to revise quickly for chemistry?