Why is sodium metal never left open in air ?

Options

A. It melts at room temperature .
B. It reacts with moisture present in air violently .
C. It reacts with oxygen present in air violently .
D. Both (b) and (c ) .

Explanation

### Step-by-Step Solution:

1. **Understanding Sodium Metal**: Sodium is a highly reactive alkali metal. It is known for its vigorous reactions, especially with water and oxygen.

2. **Reactivity with Air**: When sodium is exposed to air, it reacts with oxygen. This reaction can be quite vigorous and can lead to the formation of sodium oxide.

3. **Presence of Moisture**: While there is moisture in the air, the primary concern with sodium is its reaction with oxygen. The moisture can cause some reaction, but it is not as violent as the reaction with oxygen.

4. **Storage of Sodium**: Due to its high reactivity, sodium metal is typically stored under oil (like kerosene) to prevent it from coming into contact with air and moisture. This prevents any unwanted reactions.

5. **Conclusion**: Therefore, sodium metal is never left open in the air because it reacts violently with oxygen, which can lead to hazardous situations.

### Final Answer:
Sodium metal is never left open in air because it reacts violently with oxygen present in the air, leading to the formation of sodium oxide and potentially causing dangerous reactions.

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