Which of the following is most soluble in water ?

Options

A. `C_(2) H_(5) OH`
B. `C_(4) H_(9) OH`
C. `C_(6)H_(13) OH`
D. `C_(8) H_(17) OH`

Answer

To determine which of the given compounds is most soluble in water, we need to consider the structure of the compounds and their ability to form hydrogen bonds with water. Let's analyze the options step by step.

### Step 1: Identify the Compounds
Let's assume the options provided are:
1. Ethanol (C2H5OH)
2. Butanol (C4H9OH)
3. Hexanol (C6H13OH)
4. Octanol (C8H17OH)

### Step 2: Understand the Solubility of Alcohols
Alcohols are organic compounds that contain one or more hydroxyl (-OH) groups. The solubility of alcohols in water is influenced by:
- The size of the alkyl group (the carbon chain).
- The ability to form hydrogen bonds with water.

Lower molecular weight alcohols (those with shorter carbon chains) are generally more soluble in water because they can form hydrogen bonds effectively. As the carbon chain length increases, the hydrophobic (water-repelling) character of the alkyl group becomes more pronounced, leading to decreased solubility.

### Step 3: Analyze Each Option
- **Ethanol (C2H5OH)**: This is a lower member alcohol. It has a small carbon chain and can form hydrogen bonds with water effectively. Therefore, it is highly soluble in water.

- **Butanol (C4H9OH)**: This is a higher member alcohol compared to ethanol. While it can still form hydrogen bonds, its larger hydrophobic carbon chain reduces its solubility compared to ethanol.

- **Hexanol (C6H13OH)**: This alcohol has an even larger carbon chain than butanol, which further decreases its solubility in water.

- **Octanol (C8H17OH)**: This is the largest alcohol in the options provided. Its long carbon chain makes it the least soluble in water due to significant hydrophobic character.

### Step 4: Conclusion
Based on the analysis, **Ethanol (C2H5OH)** is the most soluble in water among the given options due to its lower molecular weight and ability to form hydrogen bonds effectively.

### Final Answer
**Ethanol (C2H5OH) is the most soluble in water.**

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