Which of the following properties among halogens decreases from fluorine to iodine ?

Options

A. Eelectronegativity
B. Electron Affinity
C. Ionisation energy
D. (1) & (3) both

Answer

To solve the question of which property among halogens decreases from fluorine to iodine, we can follow these steps:

### Step 1: Identify the Halogens
The halogens in the periodic table are fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). They are located in Group 17 of the periodic table.

### Step 2: Understand the Trends in the Group
As we move down the group from fluorine to iodine, we need to consider the following properties:
- **Electronegativity**: This is the tendency of an atom to attract electrons in a bond. Electronegativity decreases as we move down the group.
- **Ionization Energy**: This is the energy required to remove an electron from an atom. Ionization energy also decreases down the group.
- **Electron Affinity**: This is the energy change that occurs when an electron is added to a neutral atom. Electron affinity generally becomes less negative (or increases) down the group.

### Step 3: Analyze the Properties
1. **Electronegativity**: Decreases from fluorine to iodine.
2. **Ionization Energy**: Decreases from fluorine to iodine.
3. **Electron Affinity**: Increases (becomes less negative) from fluorine to iodine.

### Step 4: Conclusion
From the analysis, we can conclude that both **electronegativity** and **ionization energy** decrease from fluorine to iodine. Therefore, the properties that decrease from fluorine to iodine are:
- Electronegativity
- Ionization Energy

### Final Answer
The properties that decrease from fluorine to iodine are **electronegativity** and **ionization energy**.

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