In which element shielding effect is not possible ?

Options

A. `H`
B. `Be`
C. `B`
D. `N`

Explanation

To determine in which element the shielding effect is not possible, we need to understand what the shielding effect is and how it operates in atoms.

### Step-by-Step Solution:

1. **Define Shielding Effect**:
The shielding effect refers to the phenomenon where inner shell electrons reduce the effective nuclear charge felt by outer shell electrons. This occurs because the inner electrons repel the outer electrons, decreasing the attraction between the nucleus and the outer electrons.

2. **Identify the Requirement for Shielding**:
For the shielding effect to occur, there must be inner shell electrons present in the atom. These inner shell electrons are responsible for shielding the outer electrons from the full effect of the nuclear charge.

3. **Analyze the Given Elements**:
- **Hydrogen (H)**: Hydrogen has only one electron and no inner shell electrons. Therefore, there are no electrons to provide shielding.
- **Beryllium (Be)**: Beryllium has four electrons, with two in the first shell and two in the second shell. The inner shell electrons can shield the outer electrons.
- **Boron (B)**: Boron has five electrons, with two in the first shell and three in the second shell. The inner shell electrons can also shield the outer electrons.
- **Nitrogen (N)**: Nitrogen has seven electrons, with two in the first shell and five in the second shell. Again, the inner shell electrons can shield the outer electrons.

4. **Conclusion**:
Since hydrogen is the only element listed that has no inner shell electrons, it is the only element where the shielding effect is not possible. Thus, the correct answer is **Hydrogen (H)**.

### Final Answer:
The element in which shielding effect is not possible is **Hydrogen (H)**.

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