Which of the following compounds act as Lewis acid as well as Lewis base?

Options

A. `SO_(2)`
B. `SnCl_(2)`
C. `SnCl_(4)`
D. `NH_(3)`

Explanation

To determine which compounds act as both Lewis acids and Lewis bases, we need to analyze their structures and the presence of lone pairs and vacant orbitals.

### Step-by-Step Solution:

1. **Understanding Lewis Acids and Bases**:
- A Lewis acid is a substance that can accept an electron pair.
- A Lewis base is a substance that can donate an electron pair.

2. **Analyzing SO2**:
- The structure of SO2 (sulfur dioxide) is represented as O=S=O, with sulfur having a lone pair of electrons.
- The lone pair on sulfur allows SO2 to act as a Lewis base by donating that pair.
- Additionally, the sulfur atom can accept electron pairs due to its ability to expand its octet (it has vacant d orbitals), allowing SO2 to also act as a Lewis acid.

3. **Analyzing SOCl2**:
- The structure of SOCl2 (sulfuryl chloride) is similar to SO2, with sulfur bonded to two chlorine atoms and one oxygen atom.
- Like SO2, SOCl2 has a lone pair on sulfur, enabling it to act as a Lewis base.
- The vacant d orbitals on sulfur also allow SOCl2 to accept electron pairs, thus functioning as a Lewis acid.

4. **Analyzing SOCl4**:
- The structure of SOCl4 (sulfur tetrachloride) consists of sulfur bonded to four chlorine atoms.
- SOCl4 does not have a lone pair on sulfur, which means it cannot act as a Lewis base.
- However, it has vacant d orbitals, allowing it to act as a Lewis acid.

5. **Analyzing NH3**:
- The structure of NH3 (ammonia) has a nitrogen atom with a lone pair of electrons.
- NH3 can donate this lone pair, making it a Lewis base.
- However, NH3 does not have vacant d orbitals, so it cannot act as a Lewis acid.

6. **Conclusion**:
- From the analysis, SO2 and SOCl2 can act as both Lewis acids and Lewis bases due to the presence of lone pairs and vacant d orbitals.
- SOCl4 can only act as a Lewis acid, and NH3 can only act as a Lewis base.

### Final Answer:
The compounds that act as both Lewis acids and Lewis bases are **SO2 and SOCl2**.

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