Ammong the following, the element having highest ionization enthalpy as positive electron gain enthalpy is

Options

A. H
B. F
C. He
D. Na

Answer

To solve the question regarding which element has the highest ionization enthalpy and positive electron gain enthalpy, we can follow these steps:

### Step 1: Understand the Concepts
- **Ionization Enthalpy**: The energy required to remove an electron from an atom in the gaseous state.
- **Electron Gain Enthalpy**: The energy change when an electron is added to a neutral atom in the gaseous state. A positive value indicates that energy is required to add an electron.

### Step 2: Analyze the Options
Assuming the options provided are common elements, we need to consider their electronic configurations and positions in the periodic table. Elements with completely filled orbitals typically have high ionization enthalpy.

### Step 3: Identify Helium's Configuration
- Helium (He) has an electronic configuration of 1s², meaning it has a completely filled outer shell.

### Step 4: Compare Ionization Energies
- Elements with completely filled orbitals, like Helium, have high ionization energies because removing an electron from a stable configuration requires a significant amount of energy.
- Helium is located at the top right of the periodic table, where ionization enthalpy is generally highest.

### Step 5: Consider Electron Gain Enthalpy
- Helium, with its filled 1s orbital, has little to no tendency to accept an additional electron, resulting in a positive electron gain enthalpy.

### Conclusion
Based on the above analysis, the element with the highest ionization enthalpy and a positive electron gain enthalpy is **Helium (He)**.