The electron gain enthalpy ( in kJ//mol ) of fluorine, chlorine, bromine and iodine, respectively ,are :

Options

A. ` -333, -349, - 325 and - 296 `
B. ` - 296, -325, - 333 and - 349 `
C. ` - 349, - 333, - 325 and - 296 `
D. ` - 333, - 325, - 349 and - 296 `

Answer

To determine the electron gain enthalpy of fluorine, chlorine, bromine, and iodine, we need to understand the concept of electron gain enthalpy and the trends in the periodic table.

### Step-by-Step Solution:

1. **Define Electron Gain Enthalpy**:
- Electron gain enthalpy is the amount of energy released when an electron is added to an isolated gaseous atom. It is a measure of the tendency of an atom to accept an electron.

2. **Identify the Halogens**:
- The halogens in question are fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

3. **Understand the Trend in Electron Gain Enthalpy**:
- Generally, as we move down the group in the periodic table (from fluorine to iodine), the electron gain enthalpy decreases. This is because:
- The size of the atom increases, leading to increased distance between the nucleus and the added electron, which reduces the attraction.
- The increased shielding effect from inner electrons also reduces the effective nuclear charge felt by the added electron.

4. **Compare the Electron Gain Enthalpy of Halogens**:
- While fluorine is the most electronegative element, it does not have the highest electron gain enthalpy due to its small size causing electron-electron repulsion when an electron is added.
- The order of electron gain enthalpy for halogens is:
- Chlorine (Cl) > Fluorine (F) > Bromine (Br) > Iodine (I)

5. **Assign Values to Each Halogen**:
- Based on the known values of electron gain enthalpy:
- Chlorine: approximately -349 kJ/mol
- Fluorine: approximately -328 kJ/mol
- Bromine: approximately -324 kJ/mol
- Iodine: approximately -296 kJ/mol

6. **Conclusion**:
- The electron gain enthalpy values for fluorine, chlorine, bromine, and iodine respectively are:
- Chlorine: -349 kJ/mol
- Fluorine: -328 kJ/mol
- Bromine: -324 kJ/mol
- Iodine: -296 kJ/mol

### Final Answer:
The electron gain enthalpy of fluorine, chlorine, bromine, and iodine, respectively, are:
- Chlorine: -349 kJ/mol
- Fluorine: -328 kJ/mol
- Bromine: -324 kJ/mol
- Iodine: -296 kJ/mol