Which one of the following is Lewis acid?

Options

A. `CO_2`
B. `AlCl_3`
C. `FeCl_3`
D. all of these

Explanation

To determine which of the given options is a Lewis acid, we need to understand the definition of a Lewis acid. A Lewis acid is defined as a substance that can accept an electron pair from another substance.

Let's analyze the options provided:

1. **CO2 (Carbon Dioxide)**:
- CO2 is a polar molecule. The carbon atom in CO2 has a partial positive charge, while the oxygen atoms have partial negative charges. This polarity allows the carbon atom to accept an electron pair, thus behaving as a Lewis acid.

2. **AlCl3 (Aluminum Chloride)**:
- AlCl3 has an empty p-orbital due to the presence of three bonding pairs with chlorine atoms. This empty orbital allows AlCl3 to accept an electron pair, making it a Lewis acid.

3. **FeCl3 (Iron(III) Chloride)**:
- FeCl3 has a total of 8 valence electrons and can accept additional electrons to achieve a stable electronic configuration. The iron atom can accept electron pairs, which qualifies it as a Lewis acid.

Based on the analysis of all three compounds, we can conclude that all of them can act as Lewis acids.

**Final Answer**: All of the above (CO2, AlCl3, and FeCl3) are Lewis acids.

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