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1. So I'm really stuck on this question and would appreciate if anyone can help tell me how to work this out please:

A particular sample of bauxite ore contains 55% by mass of Al2O3 (Mr = 102) and no other aluminium compound. The minimum mass of this ore needed to produce 1.0 tonne of aluminium is:

A 1.8 tonne
B 1.9 tonne
C 2.9 tonne
D 3.4 tonne

Thanks
2. OK, the first thing you need to do is figure out how much pure Al2O3 you would need to make 1.0 tonne of aluminium. The mass of aluminium in Al2O3 is 54 per 102 a.u., which is 53%.

0.53x = 1
x = 1.89 tonnes of pure Al2O3

Since the ore is only 55% Al2O3:

0.55y = 1.89
y = 3.44 tonnes of bauxite

Hence, assuming I haven't done something really daft, the answer is D.

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