What is atomic number of sodium and Why is sodium metal kept under kerosene oil ?

Explanation

### Step-by-Step Solution:

1. **Identify the Atomic Number of Sodium:**
- The atomic number of sodium (Na) is 11. This means that sodium has 11 protons in its nucleus.

2. **Understanding the Electronic Configuration:**
- The electronic configuration of sodium is 1s² 2s² 2p⁶ 3s¹. This indicates that sodium has a total of 11 electrons, with one electron in the outermost shell (3s orbital).

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