Mole calculations spread across three levels. The sheets include the formulae and 9 or so questions. The easy one are gimmes for most GCSE groups, medium and hard are intended for higher abilities and A Level or IB.
I usually let pupils choose their sheet.
Hard Q7, someone asked for clarification
8 g of O = 0.5 moles
1:1 ratio n=m/Mr, 0.5=7/Mr, hence Mr is 14, Nitrogen, acidic
2:1 ratio n=m/Mr, 0.5 x 2=7/Mr, hence Mr is 7, Lithium (Li2O), a strongly basic oxide.