` CO` is absorbed by:

Options

A. (a) Alcohols
B. (b) Plants
C. An ammonical solution OF cuprous chloride
D. Nickel teracarbonYL

Answer

To determine which substance absorbs carbon monoxide (CO), we can analyze the options provided: alcohols, plants, ammonical solution of cuprous chloride, and nickel tetra carbonyl.

### Step-by-Step Solution:

1. **Understanding Carbon Monoxide (CO)**:
- Carbon monoxide is a small molecule consisting of one carbon atom and one oxygen atom. It has a triple bond between carbon and oxygen.
- CO has a lone pair of electrons on the carbon atom, which allows it to act as a Lewis base.

2. **Identifying Lewis Acids**:
- A Lewis acid is a substance that can accept an electron pair. In this case, we need to find a substance that can accept the lone pair from CO.
- Among the options, ammonical solution of cuprous chloride (CuCl in ammonia) is known to act as a Lewis acid.

3. **Reaction with Ammonical Cuprous Chloride**:
- When CO interacts with ammonical cuprous chloride, it forms a soluble complex. The reaction can be represented as:
\[ \text{Cu}_2\text{Cl}_2 + \text{CO} \rightarrow 2 \text{CuCl} + \text{complex} \]
- This indicates that CO can be absorbed by the ammonical solution of cuprous chloride.

4. **Evaluating Other Options**:
- **Alcohols**: They do not have the ability to form a complex with CO in the same manner as a Lewis acid.
- **Plants**: While plants can absorb CO2, they do not specifically absorb CO in a chemical reaction.
- **Nickel Tetra Carbonyl**: This is a complex of nickel and carbon monoxide, but it does not absorb CO in the same way as ammonical cuprous chloride.

5. **Conclusion**:
- Based on the analysis, the correct answer is that carbon monoxide is absorbed by **ammonical solution of cuprous chloride**.

### Final Answer:
Carbon monoxide (CO) is absorbed by **ammonical solution of cuprous chloride**.