Question

What is corrosion? What are the necessary conditions for corrosion? State the conditions in which corrosion is faster. [5 MARKS]

Answer 1

Corrosion and conditions for corrosion: 1 Mark
Faster corrosion: 4 Marks

The slow eating away of the surface of metal by air, moisture or any other substance around it is called corrosion of metal.
Necessary conditions for corrosion are air and water.

Some of the conditions which make corrosion faster are as follows:
1. The more active metals corrode faster.
2. The electrolytes dissolved in water enhance the rate of corrosion.
3. The presence of a metal less reactive than iron increases the rate of corrosion.
4. The presence of acidic gases such as $N{O}_2,C{O}_2$ etc. increase the rate of corrosion.