The number of pairs, in which electron affinity of the second element is more than that of the first element is ________.
(F, CI) (C,N) (O,N) (F, Ne) (B,C),(O,S) 

Answer

To solve the question regarding the number of pairs where the electron affinity of the second element is greater than that of the first element, we will analyze each pair of elements provided in the question.

### Step-by-Step Solution:

1. **Understand Electron Affinity**: Electron affinity is the amount of energy released when an electron is added to a neutral atom. Higher electron affinity indicates a greater tendency to gain an electron.

2. **Evaluate Each Pair**:
- **(F, Cl)**: Fluorine (F) has a higher electron affinity than Chlorine (Cl). Thus, this pair does not satisfy the condition.
- **(C, N)**: Carbon (C) has a lower electron affinity than Nitrogen (N). Therefore, this pair satisfies the condition.
- **(O, N)**: Oxygen (O) has a higher electron affinity than Nitrogen (N). Thus, this pair does not satisfy the condition.
- **(F, Ne)**: Fluorine (F) has a higher electron affinity than Neon (Ne), which is a noble gas and has a very low electron affinity. Thus, this pair does not satisfy the condition.
- **(B, C)**: Boron (B) has a higher electron affinity than Carbon (C). Thus, this pair does not satisfy the condition.
- **(O, S)**: Oxygen (O) has a higher electron affinity than Sulfur (S). Thus, this pair does not satisfy the condition.

3. **Count the Valid Pairs**: After evaluating all pairs, we find that only the pair (C, N) satisfies the condition where the electron affinity of the second element (N) is greater than that of the first element (C).

### Final Answer:
The number of pairs in which the electron affinity of the second element is more than that of the first element is **1**.

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