An element X belongs to fourth period and fifteenth group of the periodic table. Which one of the following is true regarding the outer- electronic configuration of X ? It has

Options

A. partially filled d-orbitals and completely filled s-orbitals.
B. completely filled s-orbitals and half-filled p-orbitals.
C. half-filled d-orbitals and completely filled s-orbitals.
D. half-filled d-orbitals and completely filled s-orbitals.

Explanation

To determine the outer electronic configuration of element X, which belongs to the fourth period and the fifteenth group of the periodic table, we can follow these steps:

### Step 1: Identify the Period and Group
- The element is in the **fourth period** and **fifteenth group** of the periodic table.

### Step 2: Determine the Outer Electron Configuration
- Elements in the **fifteenth group** (also known as Group 15 or Group V) have an outer electron configuration of **ns² np³**.
- Since element X is in the **fourth period**, the value of n (the principal quantum number) is 4.

### Step 3: Write the Configuration
- Therefore, the outer electronic configuration of element X can be written as:
\[ 4s^2 4p^3 \]

### Step 4: Analyze the Configuration
- In this configuration:
- The **4s** subshell has **2 electrons**, which means it is **completely filled**.
- The **4p** subshell has **3 electrons**, which means it is **half filled**.

### Step 5: Evaluate the Options
- Now, let's evaluate the provided options:
- **Option A**: Partially filled d orbitals and completely filled s orbitals - **Incorrect**.
- **Option B**: Completely filled s orbitals and half filled p orbitals - **Correct**.
- **Option C**: Half filled d orbitals and completely filled s orbitals - **Incorrect**.
- **Option D**: Half filled d orbitals and completely filled s orbitals - **Incorrect**.

### Conclusion
- The correct answer is **Option B**: completely filled s orbitals and half filled p orbitals.

---