UPDATE: This homework has been put on hold.
As we said in class today, the S4 Prelim exam is in less than two months. For this exam, it is very important that you can write chemical formulae. This PowerPoint should help with your revision for that:
Homework for next Monday is to go through this PowerPoint and make aure that you understand it. There will be a test on writing formulae next Monady (24th September).