Identify the process in which metals are gradually eaten by exposure to air and moisture.

Options

A. Corrosion
B. Gangue removal
C. Physical reaction
D. Reversible reaction

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the process by which metals are gradually deteriorated when they come into contact with air and moisture.

2. **Identifying the Options**: The options provided are:
- Corrosion
- Gang removal
- Physical reaction
- Reversible reaction

3. **Analyzing Each Option**:
- **Corrosion**: This is the process where metals react with moisture and air, leading to their gradual deterioration. For example, iron reacts with oxygen and moisture to form rust.
- **Gang Removal**: This refers to the process of removing impurities from ores, not related to the deterioration of metals.
- **Physical Reaction**: This involves changes that do not alter the chemical composition of substances, which does not apply to the gradual eating away of metals.
- **Reversible Reaction**: This is a type of chemical reaction where the products can revert back to the original reactants, which is not relevant to the corrosion process.

4. **Conclusion**: Based on the analysis, the correct answer is **Corrosion**, as it specifically describes the process of metals being gradually eaten away due to exposure to air and moisture.

**Final Answer**: The process in which metals are gradually eaten by exposure to air and moisture is called **Corrosion**.

---