Which of the following statements are correct?

Options

A. F is the most electronegative and Cs is the most electropositive element
B. The ionization energy of halogens decreses from F to I
C. The electron affinity of Cl is higher than that of F thorugh their electronegativities are in the reverse order
D. The electron affinity of noble gases in almost zero

Answer

To determine which statements are correct regarding periodic properties, let's analyze each statement step by step.

### Step 1: Analyze the first statement
**Statement**: Fluorine is the most electronegative, Cesium is the most electropositive element.

**Analysis**:
- Fluorine (F) is located in group 17 (halogens) and is indeed the most electronegative element due to its high effective nuclear charge and small atomic radius.
- Cesium (Cs) is in group 1 (alkali metals) and is the most electropositive element because it has the largest atomic radius and the lowest ionization energy in its group.

**Conclusion**: This statement is **correct**.

### Step 2: Analyze the second statement
**Statement**: Ionization energy decreases from Fluorine to Iodine.

**Analysis**:
- Ionization energy is the energy required to remove an electron from an atom. As we move down a group in the periodic table, the atomic size increases due to the addition of electron shells. This results in a decrease in ionization energy because the outermost electrons are further from the nucleus and experience less nuclear attraction.
- Therefore, the ionization energy does indeed decrease from fluorine to iodine.

**Conclusion**: This statement is **correct**.

### Step 3: Analyze the third statement
**Statement**: The electron affinity of Fluorine is higher than that of Chlorine, though their electronegativities are in reverse.

**Analysis**:
- Electron affinity is the energy change when an electron is added to a neutral atom. Fluorine has a high electron affinity, but due to inter-electronic repulsion in its small atomic structure, the energy released is less than that of chlorine.
- Chlorine has a slightly higher electron affinity than fluorine despite fluorine being more electronegative.

**Conclusion**: This statement is **incorrect**.

### Step 4: Analyze the fourth statement
**Statement**: The electron affinity of noble gases is almost zero.

**Analysis**:
- Noble gases have a complete valence shell, making them stable and generally unreactive. They do not readily accept electrons, and thus their electron affinity is indeed very low, often considered to be zero.
- However, it is important to note that while noble gases have very low electron affinity, it is not exactly zero but rather positive, as energy is required to add an electron.

**Conclusion**: This statement is **correct**.

### Final Summary of Statements:
1. Correct
2. Correct
3. Incorrect
4. Correct