STATEMENT-1 `:` The `19^(th)` electron in potassium atom enters into 4s-orbital than in 3d-orbital.
and
STATEMENT-2 `:` `(n+1l)` rule is followed for determining the orbital of lowest energy state.

Options

A. Statement-1 is True, Statement-2 is True, Statement-2 is a correct explanation for Statement-1
B. Statement-1 is True, Statement-2 isTrue, Statement-2 is NOT a correct explanation for Statement-1
C. Statement-1 is True, Statement-2 is False
D. Statement-1 is False , Statement-2 isTrue

Answer

To analyze the given statements regarding the potassium atom and the energy levels of its electrons, we can break down the solution into clear steps.

### Step-by-Step Solution:

1. **Understanding the Electron Configuration of Potassium**:
- Potassium (K) has an atomic number of 19, meaning it has 19 electrons.
- The electron configuration of potassium can be written as:
\[ 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^1 \]
- Thus, the 19th electron will enter the 4s orbital.

2. **Applying the (n + l) Rule**:
- The (n + l) rule helps determine the order of filling orbitals based on their energy levels.
- For the 4s orbital:
- \( n = 4 \) and \( l = 0 \) (since s has an angular momentum quantum number of 0).
- Therefore, \( n + l = 4 + 0 = 4 \).
- For the 3d orbital:
- \( n = 3 \) and \( l = 2 \) (since d has an angular momentum quantum number of 2).
- Therefore, \( n + l = 3 + 2 = 5 \).

3. **Comparing Energy Levels**:
- Since \( n + l \) for 4s (which is 4) is less than that for 3d (which is 5), the 4s orbital is of lower energy than the 3d orbital.
- As a result, the 19th electron in potassium will fill the 4s orbital before the 3d orbital.

4. **Evaluating the Statements**:
- **Statement 1**: The 19th electron in potassium enters the 4s orbital rather than the 3d orbital. This statement is true.
- **Statement 2**: The (n + l) rule is followed for determining the orbital of lowest energy state. This statement is also true.

5. **Conclusion**:
- Since both statements are true and Statement 2 correctly explains Statement 1, we conclude that both statements are true and Statement 2 is the correct explanation for Statement 1.

### Final Answer:
- **Both Statement 1 and Statement 2 are true, and Statement 2 is the correct explanation for Statement 1.**

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