Which of the following statement(s) is/are correct?

Options

A. van der waals' radius of iodine is more than its covalent radius
B. All isoelectronic ions of corresponding elements belong to the same period of the periodic table.
C. IE. Of N-atom is higher than that of O-atom, while `IE_(2)` of O-atom is higher than that of N-atom.
D. The electron affinity of fluorine is greater than that of chlorine.

Answer

To determine which of the statements regarding periodic properties are correct, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement A**: The Van der Waals radius of iodine (I) is more than its covalent radius.
- **Analysis**: The Van der Waals radius refers to the distance between two non-bonded atoms that are in close proximity, while the covalent radius is the distance between two bonded atoms. For iodine, when two iodine atoms bond (I2), they overlap, resulting in a shorter distance compared to when they are merely close together without bonding. Therefore, the Van der Waals radius is indeed greater than the covalent radius.
- **Conclusion**: This statement is **True**.

2. **Statement B**: All isoelectronic ions of corresponding elements belong to the same period of the periodic table.
- **Analysis**: Isoelectronic ions are ions that have the same number of electrons. For example, N³⁻ (10 electrons) and Na⁺ (10 electrons) are isoelectronic but belong to different periods (N is in the 2nd period and Na is in the 3rd period). Thus, isoelectronic ions do not necessarily belong to the same period.
- **Conclusion**: This statement is **False**.

3. **Statement C**: The ionization enthalpy of nitrogen (N) is higher than that of oxygen (O) for the first ionization, while the second ionization enthalpy of oxygen is higher than that of nitrogen.
- **Analysis**: The first ionization energy of nitrogen is higher than that of oxygen due to nitrogen's half-filled p subshell (2p³), which is more stable and requires more energy to remove an electron. For the second ionization, after removing one electron from nitrogen, it becomes less stable compared to oxygen, which has a half-filled configuration after its first ionization. Thus, the second ionization enthalpy of oxygen is indeed higher than that of nitrogen.
- **Conclusion**: This statement is **True**.

4. **Statement D**: The electron affinity of fluorine is greater than that of chlorine.
- **Analysis**: Electron affinity is the energy change when an electron is added to a neutral atom. Fluorine has a smaller atomic radius than chlorine, leading to greater electron-electron repulsion when an additional electron is added to fluorine's 2p subshell compared to chlorine's 3p subshell. Therefore, the electron affinity of fluorine is actually less than that of chlorine.
- **Conclusion**: This statement is **False**.

### Final Summary:
- **Correct Statements**:
- Statement A: True
- Statement C: True
- **Incorrect Statements**:
- Statement B: False
- Statement D: False

### Answer:
The correct statements are A and C.

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