many people? No just north america and canada spell it as aluminum. (and the international official scientific name is aluminium, even in america. By the way, aluminum instead of aluminium has only been the preferred spelling in north america for less than 100 years, before that the word aluminium was used in everyday life aswell)
I believe it should be accepted (since the quizes are in english, both british english and american english (and in cases of persons and places, the original name) should be accepted). But the answer should be shown as aluminium, because that is the official international name.