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.
Copper and silver get corroded in air by developing a coloured. layer. The colour of the layers respectively is

Options

A. green and black
B. brown and black
C. green and blue
D. black and green.

Explanation

To solve the question regarding the corrosion of copper and silver in air and the colors of the layers formed, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Corrosion**:
- Corrosion is the process where metals react with environmental factors such as air and moisture, leading to the formation of chemical compounds that degrade the metal.

2. **Identifying the Metals**:
...