For a p - block element, its 3d, 3s, 3p and 4s orbitals are completely filled and the differentiating electron goes to the 4p orbital. The element should have its atomic number in the range

Options

A. 13-18
B. 21-26
C. 31-36
D. 49-54

Explanation

To determine the atomic number range for the given p-block element, we need to analyze the electronic configuration and the filling of orbitals step by step.

### Step 1: Identify the filled orbitals
The question states that the 3d, 3s, 3p, and 4s orbitals are completely filled.

- The configuration for these orbitals is:
- 3s: 2 electrons
- 3p: 6 electrons
- 3d: 10 electrons
- 4s: 2 electrons

### Step 2: Write the electronic configuration
Combining the filled orbitals, we can write the electronic configuration up to this point:
- 3s² 3p⁶ 3d¹⁰ 4s²

### Step 3: Identify the next orbital
The next orbital that will be filled is the 4p orbital. The first electron that enters this orbital will be the differentiating electron.

### Step 4: Calculate the atomic number
Now, we need to calculate the atomic number corresponding to this configuration:
- The total number of electrons in the filled orbitals is:
- 2 (from 3s) + 6 (from 3p) + 10 (from 3d) + 2 (from 4s) = 20 electrons

Since the element is a p-block element, the atomic number is the total number of electrons, which is 20. The first electron in the 4p orbital corresponds to atomic number 21.

### Step 5: Determine the range of atomic numbers
The p-block elements start from atomic number 13 (Al) and go up to atomic number 18 (Ar) for the third period. However, since we are considering the 4p block, we need to find the range for the 4p elements, which includes atomic numbers 21 (Sc) to 36 (Kr).

### Conclusion
Thus, the atomic number of the element falls within the range of 31 to 36.

### Final Answer
The atomic number of the element should be in the range of **31 to 36**.