Assertion : Solubility of n-orbital of n-orbital in water decrease with increase in molecular weight .
Reason : The hydrophobic nature of alkyl chain increase.

Options

A. If assertion is true but the reason is false
B. If assertion is false but reason is true
C. If both assertion and reason are true and the reason is the correct explanation of assertion
D. If both assertion and reason are true and the reason is not the correct explanation of assertion

Answer

To solve the question, we need to analyze both the assertion and the reason provided, and determine their validity and relationship.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that the solubility of n-orbital compounds in water decreases with an increase in molecular weight.
- This is generally true because as the molecular weight of a compound increases, it often contains longer hydrophobic (non-polar) alkyl chains which do not interact favorably with water.

2. **Understanding the Reason**:
- The reason given is that the hydrophobic nature of the alkyl chain increases.
- This is also true because as the length of the alkyl chain increases, the proportion of the hydrophobic (non-polar) part of the molecule increases relative to the hydrophilic (polar) part.

3. **Connecting Assertion and Reason**:
- The assertion and reason are related. The increase in hydrophobic character due to longer alkyl chains leads to decreased solubility in water, as hydrophobic interactions do not favor solubility in polar solvents like water.

4. **Conclusion**:
- Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is that both the assertion and reason are true, and the reason is a correct explanation of the assertion.

### Final Answer:
Both the assertion and the reason are true, and the reason is a correct explanation of the assertion.