Which one of the following species is not an electropile?

Options

A. `overset(+)underset(NO_(2)`
B. `H_(3)O^(+)`
C. `CI^(+)`
D. `BH_(3)`

Answer

To determine which species is not an electrophile, we first need to understand the definition of an electrophile. An electrophile is a species that is electron-deficient and can accept an electron pair. Typically, electrophiles are positively charged or neutral species with an incomplete octet, making them capable of accepting electrons.

Let's analyze the given species one by one:

1. **NH4⁺ (Ammonium ion)**: This species has a positive charge and is electron-deficient. It can accept an electron pair, thus it is an electrophile.

2. **H⁺ (Proton)**: This species is positively charged and highly electron-deficient. It can readily accept an electron pair, making it an electrophile.

3. **BF3 (Boron trifluoride)**: Although it is neutral, boron has only six electrons in its valence shell, making it electron-deficient. It can accept an electron pair, so it is also an electrophile.

4. **CH4 (Methane)**: This species is neutral and has a complete octet around carbon. It does not have any electron deficiency and cannot accept an electron pair, making it not an electrophile.

Based on this analysis, the species that is not an electrophile is **CH4 (Methane)**.

### Step-by-Step Solution:
1. **Understand the definition of an electrophile**: An electrophile is an electron-deficient species that can accept an electron pair.
2. **Analyze each species**:
- NH4⁺: Positive charge, electron-deficient, electrophile.
- H⁺: Positive charge, highly electron-deficient, electrophile.
- BF3: Neutral, electron-deficient, electrophile.
- CH4: Neutral, complete octet, not electron-deficient, not an electrophile.
3. **Identify the species that is not an electrophile**: CH4 (Methane).