Chemical formula of rust is:

Options

A. `Fe_(2)O_(3). H_(2)O`
B. `Fe_(2)O_(3). 5H_(2)O`
C. `Fe_(2)O_(3).xH_(2)O`
D. None of these

Explanation

To determine the chemical formula of rust, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Rust**: Rust is a product formed when iron reacts with oxygen in the presence of moisture (water). This process is known as rusting or corrosion.

2. **Chemical Reaction**: When iron (Fe) is exposed to oxygen (O2) and water (H2O), it undergoes oxidation. The primary product of this reaction is iron oxide.

3. **Identifying the Compound**: The most common form of rust is hydrated iron(III) oxide. The general formula for rust can be expressed as Fe2O3·xH2O, where "x" represents the number of water molecules associated with the iron oxide.

4. **Final Formula**: Therefore, the chemical formula of rust is Fe2O3·xH2O, indicating that it is iron(III) oxide combined with water.

### Conclusion:
The chemical formula of rust is **Fe2O3·xH2O**.

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