Which one of the following statements is incorrect?

Options

A. Greater is the nuclear, greater is the electron affinity.
B. Neon has zero electron affinity.
C. Electron affinity decreases from fluorine to iodine in the group
D. Electron affinity decreases in going down a group and increases across from the left to the right `(rarr)`.

Explanation

To determine which statement is incorrect regarding electron affinity, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement:** Greater the nuclear charge, greater the electron affinity.

- **Explanation:** Electron affinity is the energy change that occurs when an atom gains an electron. As we move across a period from left to right, the nuclear charge increases, which generally leads to a stronger attraction between the nucleus and the incoming electron. Thus, this statement is correct.

### Step 2: Analyze the second statement
**Statement:** Neon has zero electron affinity.

- **Explanation:** Neon is a noble gas with a fully filled outer shell, making it stable and unlikely to gain additional electrons. Therefore, it has zero electron affinity. This statement is also correct.

### Step 3: Analyze the third statement
**Statement:** Electron affinity decreases from fluorine to iodine in a group.

- **Explanation:** In a group, as we move down from fluorine to iodine, the atomic size increases, which generally leads to a decrease in electron affinity. However, it is important to note that fluorine has a lower electron affinity than chlorine due to its small size and high electron-electron repulsion in its compact structure. Therefore, this statement is misleading because it implies a straightforward trend without acknowledging the exception of fluorine and chlorine. This statement is incorrect.

### Step 4: Analyze the fourth statement
**Statement:** Electron affinity decreases in going down the group and increases across from left to right.

- **Explanation:** This statement is correct. As we move down a group, the atomic size increases, leading to a decrease in electron affinity. Conversely, as we move across a period from left to right, the nuclear charge increases, leading to an increase in electron affinity.

### Conclusion
Based on the analysis, the incorrect statement is the third one: "Electron affinity decreases from fluorine to iodine in a group."

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