Corrosion may be defined as the process of slow eating up of a metal by the gases and water vapours present in air due to formation of certain chemical compounds.
Corrosion is favoured by the following factors:
(i) Position of metal in the reactivity series: Active metals placed above hydrogen in the reactivity series are easily corroded as compared to the metals which are placed below hydrogen.
(ii) Air and moisture: The presence of water vapours and gases like `CO_(2), SO_(2)` etc. in air helps the process of corrosion.
(iii) Uneven metal surface: If the surface of metal is uneven, it will have certain depressions. Water drops will stick in these and take part in the chemical process leading to corrosion.
(iv) Presence of salts: Presence of salts or electrolytes in water promotes corrosion. For example, rusting of iron is faster in sea water (also called saline water) than in ordinary water or distilled water.
Following processes are very common for checking rusting of iron

Options

A. galvanisation
B. tinning
C. electroplating
D. all of these.

Explanation

To address the question regarding common processes for checking rusting of iron, we can outline the following steps:

### Step-by-Step Solution:

1. **Understanding Rusting**:
- Rusting is the process where iron reacts with oxygen and moisture in the environment, leading to the formation of iron oxide (rust). This process degrades the properties of iron, such as its strength and appearance.

2. **Identifying Methods to Prevent Rusting**:
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