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 metal A of which the object is made.

Answer

To solve the question step by step, let's break down the information provided:

1. **Identify Metal A**: The question states that a grey-colored object made of metal A gets covered with a red-brown flaky coating when exposed to damp air. This red-brown flaky coating is commonly known as rust. Rust is primarily formed when iron reacts with oxygen and water.

**Hint**: Think about common metals that can rust when exposed to moisture and air.

2. **Process B**: The process by which the red-brown flaky coating forms is known as rusting. Rusting is a chemical change where iron reacts with oxygen in the presence of water to form iron oxide, which is the flaky red-brown substance.

**Hint**: Consider the name of the process that describes the deterioration of iron due to moisture and oxygen.

3. **Identify C and D**: The presence of C and D is necessary for the process of rusting to occur. In this context, C can be identified as oxygen and D as water. Both are essential for rusting to take place.

**Hint**: Recall the components that are required for rusting to happen.

4. **Metal E and Galvanization**: The question mentions that if the object is galvanized by metal E, the process of rusting does not occur. Galvanization is a method of protecting iron from rusting by coating it with a layer of zinc (metal E). Zinc acts as a protective barrier and prevents moisture and oxygen from reaching the iron.

**Hint**: Think about metals that are commonly used to coat iron to prevent rusting.

5. **Conclusion**: Based on the above analysis, we conclude that metal A is iron.

**Final Answer**: The metal A of which the object is made is **iron**.