The decay of metals by atmospheric oxygen and moisture is called corrosion. Few metals do not react with atmospheric gases and water and do not undergo corrosion, while others develop a dull layer on them or a coloured layer to spoil their shiny appearance or turn black or are converted into powder. few elements, on the other hand are protected due to presence of this dull layer of oxide on them.
Q. Silver metal on exposure to air for a long time becomes black in colour. what is the reason behind it ?

Explanation

**Step-by-Step Solution:**

1. **Understanding Corrosion**: Corrosion is the process where metals deteriorate due to reactions with environmental factors such as oxygen and moisture.

2. **Identifying the Metal**: In this case, we are focusing on silver metal and its behavior when exposed to air over time.

3. **Exposure to Air**: When silver is exposed to air, it interacts with various components present in the atmosphere. One of these components is sulfur, which is found in trace amounts in the air.

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