What is false for most alkyl halides?

Options

A. These are completely soluble in water
B. These give nucleophilic substitution reactions
C. These are insoluble in water
D. These are soluble in organic solvents

Answer

To determine what is false for most alkyl halides, we need to analyze the given options based on the properties of alkyl halides.

### Step-by-Step Solution:

1. **Understanding Alkyl Halides**:
Alkyl halides are compounds with the general formula R-X, where R is an alkyl group and X is a halogen (like Cl, Br, or I).

2. **Option 1: Completely soluble in water**:
- Alkyl halides are generally not completely soluble in water. While smaller alkyl halides may have some solubility due to their polar nature (due to the halogen), the larger alkyl groups are hydrophobic and repel water. Therefore, this option is likely false.

3. **Option 2: Give nucleophilic substitution reactions**:
- Alkyl halides do undergo nucleophilic substitution reactions. The carbon-halogen bond is polar, making the carbon atom susceptible to attack by nucleophiles. This statement is true.

4. **Option 3: Insoluble in water**:
- As discussed, alkyl halides are generally insoluble in water, especially larger ones due to their hydrophobic nature. This statement is true.

5. **Option 4: Soluble in organic solvents**:
- Alkyl halides are soluble in organic solvents, particularly those with low polarity. This is because the interactions between alkyl halides and organic solvents are comparable in strength to the interactions being broken. This statement is true.

### Conclusion:
The false statement regarding alkyl halides is **Option 1: They are completely soluble in water**.