Which of the following statements is correct? Rusting of iron is a chemical change because

Options

A. a new substance with new properties is produced
B. chemical composition of reactant is changed
C. change is permanent and can not be reversed easily
D. all of these.

Explanation

To determine why rusting of iron is a chemical change, let's analyze the process step by step.

### Step-by-Step Solution:

1. **Understanding Rusting**:
Rusting of iron occurs when iron reacts with oxygen in the presence of moisture (water). The chemical reaction can be represented as:
\[ 4Fe + 3O_2 + 6H_2O \rightarrow 4Fe(OH)_3 \]
Upon further oxidation, this can form hydrated ferric oxide, commonly known as rust (Fe₂O₃·nH₂O).

2. **Formation of New Substances**:
During rusting, new substances are formed. The original iron (Fe) is transformed into rust (Fe₂O₃·nH₂O), which has different properties compared to iron. This indicates a chemical change because a new substance with different chemical properties is produced.

3. **Change in Chemical Composition**:
The reactants (iron and oxygen) undergo a change in their chemical composition. The iron atoms combine with oxygen atoms to form a completely different compound (rust), which is a clear indication of a chemical change.

4. **Irreversibility of the Change**:
Rusting is a permanent change. Once iron has rusted, it cannot be reverted back to its original metallic state easily. This irreversibility is a characteristic feature of chemical changes.

5. **Comparison of Properties**:
The properties of rust are entirely different from those of iron. For example, rust is brittle and has a reddish-brown color, whereas iron is a shiny, malleable metal. This change in properties further confirms that rusting is a chemical change.

### Conclusion:
Based on the analysis above, we can conclude that rusting of iron is a chemical change because:
- A new substance with new properties is produced.
- The chemical composition of the reactants is changed.
- The change is permanent and cannot be reversed.