When a grey coloured object made of metal A is left exposed to damp air for a considerable time, it gets covered with a red-brown flaky coating by the process called B which eats up the whole object gradually. It is said that the presence of C and D is necessary for this process to take place. If this object is galvanised by metal E, then the process B does not occur.
Name the process B.

Answer

### Step-by-Step Solution:

1. **Identify the Object**: The object in question is a grey-colored metal, referred to as metal A. Based on the context, this metal is likely iron.

2. **Observation of Change**: When metal A (iron) is left exposed to damp air for a long time, it develops a red-brown flaky coating. This coating is commonly known as rust.

3. **Name the Process**: The process by which iron reacts with moisture and oxygen in the air to form rust is called **rusting**. Therefore, process B is rusting.

4. **Identify Necessary Conditions**: The presence of C and D is necessary for rusting to occur. In this context:
- C is **oxygen** (O2) from the air.
- D is **water** (H2O) from the damp air.

5. **Galvanization**: The question states that if metal A is galvanized by metal E, the process B (rusting) does not occur. Galvanization involves coating iron (metal A) with zinc (metal E) to prevent rusting.

6. **Conclusion**: Thus, the final answer is:
- Process B is **rusting**.

### Summary:
- Metal A: Iron
- Process B: Rusting
- Necessary conditions: C (Oxygen) and D (Water)
- Metal E (used for galvanization): Zinc