Which metal is used as a coating on steel to prevent corrosion where the cell reactions are:-

Options

A. Fe is oxidised to `Fe^(2+)` and issolved oxygen oxygen in water is reduced to `overset(Ө)(O)H`
B. Fe is oxidised to `Fe^(3+) and H_(2)O` is reduced to `O_(2)^(2-)`
C. Fe is oxidised to `Fe^(2+) and H_(2)O` is reduced to `O_(2)^(-)`
D. Fe is oxidised to `Fe^(2+) and H_(2)O` is reduced to `O_(2)`

Explanation

To determine which metal is used as a coating on steel to prevent corrosion, we can analyze the cell reactions provided and the properties of various metals.

### Step-by-Step Solution:

1. **Understanding Corrosion**: Corrosion is an electrochemical process where metals react with environmental elements (like oxygen and moisture) leading to degradation. Steel, primarily composed of iron (Fe), is prone to corrosion.

2. **Identifying the Anode Reaction**: In the provided cell reactions, the anode reaction involves the oxidation of iron:
\[ \text{Fe} \rightarrow \text{Fe}^{2+} + 2e^- \]
This indicates that iron loses electrons and forms iron ions, which is a key step in the corrosion process.

3. **Identifying the Cathode Reaction**: The cathode reaction involves the reduction of oxygen in the presence of water:
\[ \text{O}_2 + 2\text{H}_2\text{O} + 4e^- \rightarrow 4\text{OH}^- \]
This shows that oxygen is being reduced, which contributes to the overall corrosion process.

4. **Overall Reaction**: The overall reaction combining both anode and cathode processes can be summarized as:
\[ 2\text{Fe} + \text{O}_2 + 2\text{H}_2\text{O} \rightarrow 4\text{OH}^- + 2\text{Fe}^{2+} \]
This indicates that iron is being oxidized while oxygen is being reduced.

5. **Coating to Prevent Corrosion**: To prevent corrosion, a protective coating is applied to steel. One of the most common metals used for this purpose is zinc. Zinc acts as a sacrificial anode; it oxidizes preferentially over iron, thus protecting the steel underneath.

6. **Conclusion**: The metal used as a coating on steel to prevent corrosion is **Zinc (Zn)**.