Alcohols of low molecular weight are

Options

A. soluble in water
B. soluble in water on heating
C. insoluble in water
D. insoluble in all solvents.

Answer

To solve the question regarding the solubility of low molecular weight alcohols in water, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Alcohol Structure**:
- Alcohols are organic compounds that contain one or more hydroxyl (-OH) groups. The simplest alcohol is methanol (CH3OH), followed by ethanol (CH3CH2OH), and so on.

2. **Analyzing Molecular Weight**:
- Low molecular weight alcohols typically refer to those with fewer carbon atoms in their hydrocarbon chain. For example, methanol and ethanol are considered low molecular weight alcohols.

3. **Hydrophobic vs. Hydrophilic Parts**:
- Alcohols consist of a hydrophilic (water-attracting) hydroxyl group and a hydrophobic (water-repelling) hydrocarbon chain. The hydroxyl group can form hydrogen bonds with water, while the hydrocarbon part does not interact favorably with water.

4. **Effect of Hydrocarbon Chain Length**:
- As the length of the hydrocarbon chain increases, the hydrophobic character of the alcohol increases, which reduces its overall solubility in water. For instance, methanol is highly soluble, while butanol (C4H9OH) is less soluble.

5. **Hydrogen Bonding**:
- The solubility of alcohols in water is largely due to hydrogen bonding between the hydroxyl group of the alcohol and water molecules. The more effective the hydrogen bonding, the higher the solubility.

6. **Conclusion**:
- Therefore, low molecular weight alcohols (like methanol and ethanol) are soluble in water because they have a greater proportion of hydrophilic -OH groups compared to their hydrophobic hydrocarbon chains. As the molecular weight increases, the solubility decreases due to the increased hydrophobic character.

7. **Final Answer**:
- The correct answer is that low molecular weight alcohols are **soluble in water**.