STATEMENT-1 `:` Principal Quantum number of outermost electron in Fe is 4.
and
STATEMENT-2 `:` Last electron is filled in 3d.

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 solve the question regarding the two statements about the principal quantum number of the outermost electron in iron (Fe) and the filling of the last electron in the 3d subshell, we will analyze each statement step by step.

### Step-by-Step Solution:

**Step 1: Determine the Atomic Number of Iron (Fe)**
- The atomic number of iron (Fe) is 26. This means that iron has 26 electrons.

**Step 2: Write the Electron Configuration of Iron**
- The electron configuration of iron can be written as:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶
- This configuration shows how the electrons are distributed among the various energy levels and subshells.

**Step 3: Identify the Outermost Electron and Its Principal Quantum Number**
- The outermost electrons are those in the highest principal quantum number (n). In the electron configuration, the outermost shell for iron is the 4s subshell.
- The principal quantum number (n) for the 4s subshell is 4. Therefore, the statement "the principal quantum number of the outermost electron in Fe is 4" is **true**.

**Step 4: Analyze the Last Electron Filling**
- The last electron in the electron configuration of iron is filled in the 3d subshell (3d⁶). According to the Aufbau principle, electrons fill the lowest energy orbitals first.
- The statement "the last electron is filled in 3d" is also **true**.

**Step 5: Evaluate the Relationship Between the Two Statements**
- While both statements are true, Statement 2 does not provide a correct explanation for Statement 1. The principal quantum number of the outermost electron being 4 is a fact based on its position in the electron configuration, while the filling of the last electron in 3d is a separate fact regarding electron configuration order.

**Conclusion: Determine the Correct Option**
- Since both statements are true, but Statement 2 does not explain Statement 1, the correct option is:
- **Option B**: Statement 1 is true, Statement 2 is true, but Statement 2 is not a correct explanation for Statement 1.