The explanation for the presence of three unpaired electrons in the nitrogen atom can be given by -

Options

A. Pauli's exclusions principle
B. Hund's rule
C. Aufbau's principle
D. Uncertainty principle

Explanation

To explain the presence of three unpaired electrons in the nitrogen atom, we can follow these steps:

### Step 1: Understand the Electron Configuration of Nitrogen
- The atomic number of nitrogen (N) is 7, which means it has 7 electrons.
- The electron configuration of nitrogen can be written as:
- 1s² 2s² 2p³

### Step 2: Identify the Electron Distribution
- In the electron configuration:
- The 1s orbital is filled with 2 electrons (1s²).
- The 2s orbital is filled with 2 electrons (2s²).
- The 2p orbital has 3 electrons (2p³).

### Step 3: Apply Hund's Rule
- According to Hund's Rule, electrons will fill degenerate orbitals (orbitals of the same energy level) singly before pairing up.
- In the case of nitrogen, the 2p subshell has three orbitals (2p_x, 2p_y, 2p_z).
- Each of these three orbitals will receive one electron before any pairing occurs.

### Step 4: Conclusion
- As a result, nitrogen has three unpaired electrons in its 2p orbitals, which can be represented as:
- 2p: ↑ ↑ ↑ (one electron in each of the three 2p orbitals)
- Therefore, the presence of three unpaired electrons in nitrogen is explained by Hund's Rule.

### Final Answer
The explanation for the presence of three unpaired electrons in the nitrogen atom can be given by Hund's Rule.

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