Which of the following is an electrophile ?
`NH_3`
`AlCl_3`
`OH^(-)`
`CH_3-O-CH_3`

Options

A. `NH_3`
B. `AlCl_3`
C. `OH^(-)`
D. `CH_3-O-CH_3`

Explanation

To determine which of the given substances is an electrophile, we need to understand the definition of an electrophile and analyze each option accordingly.

### Step-by-Step Solution:

1. **Understanding Electrophiles**:
- Electrophiles are species that are electron-deficient and can accept electrons from nucleophiles. They typically have a positive charge or a partial positive charge.

2. **Analyzing Each Option**:
- **Option 1: NH₃ (Ammonia)**:
- Ammonia has a nitrogen atom with a lone pair of electrons, making it a nucleophile (electron donor). It does not qualify as an electrophile.

- **Option 2: AlCl₃ (Aluminum Chloride)**:
- Aluminum has three valence electrons and shares them with three chlorine atoms. This results in aluminum having only six electrons in its valence shell, making it electron-deficient. Therefore, AlCl₃ acts as an electrophile.

- **Option 3: OH⁻ (Hydroxide Ion)**:
- The hydroxide ion has a negative charge and a lone pair of electrons, making it a strong nucleophile. It cannot be classified as an electrophile.

- **Option 4: CH₃-O-CH₃ (Dimethyl Ether)**:
- In dimethyl ether, the oxygen atom has two lone pairs of electrons, which it can donate, thus acting as a nucleophile. It is not an electrophile.

3. **Conclusion**:
- Among the given options, only **AlCl₃ (Aluminum Chloride)** is an electrophile.

### Final Answer:
**AlCl₃ (Aluminum Chloride)** is the electrophile.