Which one of the following arrangements does not give the correct picture of the trends indicated against it ?

Options

A. `F_(2) gt Cl_(2) gt Br_(2) gt I_(2)` Bond dissoviation energy
B. `F_(2) gt Cl_(2) gt Br_(2) gt I_(2)` Electronegativity
C. `F_(2) gt Cl_(2) gt Br_(2) gt I_(2)` Oxidizing power
D. `F_(2) gt Cl_(2) gt Br_(2) gt I_(2)` Electron gain enthalpy

Explanation

To solve the question regarding the correct trends of bond dissociation energy, electronegativity, oxidizing power, and electron gain enthalpy for halogens, we need to analyze each trend one by one.

### Step-by-Step Solution:

1. **Bond Dissociation Energy**:
- The bond dissociation energy refers to the energy required to break a bond between two atoms. For halogens, the order of bond dissociation energy is:
\[ \text{Cl}_2 > \text{Br}_2 > \text{I}_2 > \text{F}_2 \]
- This order is correct because Cl2 has a strong bond due to its optimal size and electron repulsion, while I2 has a weaker bond due to larger atomic size and increased electron repulsion.

2. **Electronegativity**:
- Electronegativity is the tendency of an atom to attract electrons. The correct order for halogens is:
\[ \text{F} > \text{Cl} > \text{Br} > \text{I} \]
- This order is correct as fluorine is the most electronegative element, followed by chlorine, bromine, and iodine.

3. **Oxidizing Power**:
- The oxidizing power of halogens indicates their ability to gain electrons. The correct order is:
\[ \text{F}_2 > \text{Cl}_2 > \text{Br}_2 > \text{I}_2 \]
- This order is correct because fluorine is the strongest oxidizing agent, followed by chlorine, bromine, and iodine.

4. **Electron Gain Enthalpy**:
- The electron gain enthalpy is the energy change when an electron is added to a neutral atom. The correct order for halogens is:
\[ \text{Cl} > \text{F} > \text{Br} > \text{I} \]
- This order is incorrect as typically, fluorine should have the highest electron gain enthalpy due to its small size and high electronegativity. However, chlorine has a higher electron gain enthalpy than fluorine due to less electron-electron repulsion in its larger atomic size.

### Conclusion:
Based on the analysis, the arrangement that does not give the correct picture of the trends indicated against it is related to the electron gain enthalpy, which is incorrect. Therefore, the final answer is:

**Answer**: The arrangement that does not give the correct picture is related to the electron gain enthalpy.

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