Give reason:
Sodium, potassium and lithium are stored under oil

Explanation

**Step-by-Step Solution:**

1. **Identify the Metals**: Sodium (Na), Potassium (K), and Lithium (Li) are all alkali metals found in Group 1 of the periodic table.

2. **Understand Their Reactivity**: These metals are known for their high reactivity, especially with water and oxygen. When exposed to air, they can react vigorously, leading to combustion or explosions.

3. **Reason for Storage**: To prevent these metals from reacting with oxygen in the air, they are stored under oil. The oil acts as a barrier, preventing contact with air.

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