Which property of hydrogen is shown by the following reaction ?
(i) `Fe_(3)O_(4) + 4H_(2) rarr 3Fe + 4H_(2)O`
(ii) `CO + H_(2) overset ("ZnO,")underset(Cr_(r )O_(3))rarr CH_(3) OH`

Options

A. reducing character
B. Oxidising character
C. Combustibility
D. High reactivity

Explanation

To determine the property of hydrogen demonstrated by the given reactions, we can analyze each reaction step by step.

### Step 1: Analyze the First Reaction
The first reaction is:
\[ \text{Fe}_3\text{O}_4 + 4\text{H}_2 \rightarrow 3\text{Fe} + 4\text{H}_2\text{O} \]

- **Identify the Reactants and Products**:
- Reactants: Iron(II,III) oxide (Fe3O4) and hydrogen (H2).
- Products: Iron (Fe) and water (H2O).

- **Determine the Change in Oxidation States**:
- In Fe3O4, iron has an oxidation state of +2 and +3.
- In the products, elemental iron (Fe) has an oxidation state of 0.
- Hydrogen (H2) is being oxidized to form water (H2O).

- **Conclusion**:
- Since Fe3O4 is reduced to Fe, hydrogen acts as a reducing agent in this reaction.

### Step 2: Analyze the Second Reaction
The second reaction is:
\[ \text{CO} + \text{H}_2 \overset{\text{ZnO}}{\underset{\text{Cr}_2\text{O}_3}{\rightarrow}} \text{CH}_3\text{OH} \]

- **Identify the Reactants and Products**:
- Reactants: Carbon monoxide (CO) and hydrogen (H2).
- Products: Methanol (CH3OH).

- **Determine the Change in Oxidation States**:
- In CO, carbon has an oxidation state of +2.
- In methanol (CH3OH), carbon has an oxidation state of -2.
- Hydrogen is again acting to reduce the carbon from CO to CH3OH.

- **Conclusion**:
- Here, hydrogen also acts as a reducing agent since it reduces CO to CH3OH.

### Final Conclusion
Both reactions demonstrate that hydrogen acts as a reducing agent. Therefore, the property of hydrogen shown by these reactions is its **reducing character**.

### Summary of Solution
The property of hydrogen demonstrated by the reactions is its reducing character, as it reduces Fe3O4 to Fe and CO to CH3OH.

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