Which of the following statements is incorrect ?

Options

A. The ionization potential of nitrogen is greater than of oxygen
B. The electron affinity of fluorine is greater than of chlorine .
C. The ionization potential of Mg is greater than aluminium
D. The electronegativity of fluorine is greater than that of chlorine

Answer

To determine which statement is incorrect, we will analyze each provided statement one by one.

### Step-by-Step Solution:

1. **Statement 1: The ionization potential of nitrogen is greater than that of oxygen.**
- **Analysis:**
- Nitrogen (N) has an atomic number of 7 and an electronic configuration of 1s² 2s² 2p³.
- Oxygen (O) has an atomic number of 8 and an electronic configuration of 1s² 2s² 2p⁴.
- Nitrogen has a half-filled p-orbital (2p³), which is more stable than the partially filled p-orbital of oxygen (2p⁴).
- Therefore, more energy is required to remove an electron from nitrogen than from oxygen.
- **Conclusion:** This statement is **correct**.

2. **Statement 2: The electron affinity of fluorine is greater than that of chlorine.**
- **Analysis:**
- Fluorine (F) is smaller in size compared to chlorine (Cl), leading to higher inter-electronic repulsion when an electron is added to fluorine.
- Although fluorine generally has a high electron affinity, the repulsion makes its electron affinity lower than that of chlorine.
- **Conclusion:** This statement is **incorrect**.

3. **Statement 3: The ionization potential of magnesium is greater than that of aluminum.**
- **Analysis:**
- Magnesium (Mg) has an atomic number of 12 and an electronic configuration of 1s² 2s² 2p⁶ 3s².
- Aluminum (Al) has an atomic number of 13 and an electronic configuration of 1s² 2s² 2p⁶ 3s² 3p¹.
- Magnesium has a fully filled 3s orbital, while aluminum has a partially filled 3p orbital.
- It is easier to remove an electron from aluminum than from magnesium, indicating that magnesium has a higher ionization potential.
- **Conclusion:** This statement is **correct**.

4. **Statement 4: The electronegativity of fluorine is greater than that of chlorine.**
- **Analysis:**
- Fluorine is the most electronegative element in the periodic table, with a value of 4.0 on the Pauling scale, while chlorine has a lower electronegativity.
- **Conclusion:** This statement is **correct**.

### Final Conclusion:
The incorrect statement among the options is **Statement 2: The electron affinity of fluorine is greater than that of chlorine.**