Question

Which of the following oxides cannot be reduced with carbon monoxide?
A. `Fe_(3)O_(3)`
B. `Al_(2)O_(3)`
C. `CuO`
D. `NiO`

Answer 1

Correct Answer - B
Since `CO` can be easily oxidized to `CO_(2)`, it acts as a good reducing agent and can reduce the oxides of less electropositive metals to the corresponding metals:
`Fe_(2)O_(3) + 3CO overset("Blast furnace")rarr 2Fe + 3CO_(2)`
`CuO + CO rarr Cu + CO_(2)`
`Al` is quite electropositive.