The red or Orange coating that forms on the surface of iron when exposed to air and moisture for some time is called

Options

A. galvanisation
B. electroplating
C. rust
D. reduction

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the name of the red or orange coating that appears on iron when it is exposed to air and moisture over time.

2. **Identifying the Process**: The phenomenon described is known as corrosion. Corrosion occurs when metals react with their environment, leading to the formation of metal oxides.

3. **Specific Case of Iron**: When iron is exposed to moist air, it undergoes corrosion, resulting in the formation of a specific oxide.

4. **Naming the Coating**: The red or orange coating that forms on iron due to this corrosion is called "rust."

5. **Chemical Composition of Rust**: Rust is primarily composed of iron oxide, and its chemical formula is represented as Fe2O3·xH2O, where 'x' indicates the number of water molecules associated with the iron oxide.

6. **Conclusion**: Therefore, the answer to the question is that the red or orange coating on iron is called "rust."

---