The correct option is (c).
Explanation
Rusting is a chemical process involving the corrosion of iron. It is an oxidation reaction where iron reacts with atmospheric oxygen in the presence of moisture to form a reddish-brown substance known as rust.
Statement-wise Analysis
- Statement 1 is Incorrect. Rust and iron are not the same substance. Iron is a chemical element (Fe), whereas rust is a chemical compound called hydrated iron(III) oxide ($Fe_2O_3 \cdot xH_2O$). The formation of rust is a chemical change resulting in a new substance with properties different from the original metal.
- Statement 2 is Correct. The process of rusting requires two essential conditions: the presence of oxygen (usually from the air) and the presence of water (or moisture). If either of these components is absent, rusting does not occur.
- Statement 3 is Correct. Humidity refers to the amount of water vapour present in the air. High humidity implies a higher concentration of moisture, which facilitates the electrochemical process of corrosion. Therefore, the rate of rusting is significantly faster in humid environments compared to dry environments.
Key Takeaway
Rusting is the formation of hydrated iron oxide ($Fe_2O_3 \cdot xH_2O$) from iron. It is a chemical change that strictly requires both oxygen and water to proceed.