[rickyponting66]

Which substance cannot reduce iron (III) oxide to iron?
a) Carbon dioxide
b) Carbon monoxide
c) Coke (carbon)
d) Hydrogen

[SirRoderick]

Kind of odd you would post a multiple choice question, but hey.

Carbon, Carbon monoxide and Hydrogen I believe can reduce Iron(III) to Iron. So then the awnser would be CO₂. I'm not looking at the tables right now, but if memory serves that should be correct.

[DevaDevil]

a substance which can reduce iron (III) has to be oxidized itself of course. So this question can also be read as: which compound can be oxidised?

you will see that carbon dioxide has carbon in its fully-oxidised 4+ state and cannot oxidise further, therefore it cannot reduce iron (III)

[SirRoderick]

a substance which can reduce iron (III) has to be oxidized itself of course. So this question can also be read as: which compound can be oxidised?

you will see that carbon dioxide has carbon in its fully-oxidised 4+ state and cannot oxidise further, therefore it cannot reduce iron (III)

Should have thought of that actually, good way to rule it out. Still, memory did serve!