Question

Which statement is incorrect for the reaction $\mathrm{CuO}+{\mathrm{H}}_2\to \mathrm{Cu}+{\mathrm{H}}_2\mathrm{O}$

• A. CuO is reduced
• B. ${\mathrm{H}}_2$ is oxidized
• C. CuO is reduced and ${\mathrm{H}}_2$ is oxidized
• D. Both CuO and ${\mathrm{H}}_2$ are oxidized

Answer 1

The correct option is D

Both CuO and ${\mathrm{H}}_2$ are oxidized

Explanation for correct answer
D. 1. Oxidation can be defined as the addition of oxygen or removal of electrons to or from an atom, respectively.

2. Reduction can be defined as the removal of oxygen or the addition of electrons from or to the atom, respectively.

In the given reaction, CuO is converted to Cu (copper), and hence, it is reduced as the removal of the oxygen atom occurs. The oxidation number of Cu changes from +2 to 0. Also, Hydrogen $\left({\mathrm{H}}_2\right)$ is converted to Water $\left({\mathrm{H}}_2\mathrm{O}\right)$ which shows the change in oxidation number from 0 to +1. This shows that ${\mathrm{H}}_2$ is oxidized. Thus, Copper oxide (CuO) is reduced and Hydrogen $\left({\mathrm{H}}_2\right)$ is oxidized.

Explanation for incorrect answer

The given reaction shows that the conversion of copper oxide to copper is a reduction reaction and CuO is reduced, not oxidized. Hence, sentences A and C are correct. Similarly, hydrogen converted to water shows that it is oxidized and not reduced. So, sentence B is also correct. Then the only incorrect sentence is D.

Therefore, the correct option is D. Both CuO and ${\mathrm{H}}_2$ are oxidized.