A: Due to ortho effect basic nature of aniline decreases.
R: It is due to steric hinderance because of solvation of cation.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements, then mark (4)

Answer

To solve the question, we need to analyze the assertion and reason provided regarding the basic nature of aniline and the ortho effect. Here’s a step-by-step breakdown of the solution:

### Step 1: Understanding the Assertion
The assertion states that "due to ortho effect, the basic nature of aniline decreases."
- **Explanation**: Aniline, which is an aromatic amine, has a lone pair of electrons on the nitrogen atom. This lone pair can participate in protonation, which is a measure of basicity. However, when there are substituents at the ortho position, they can interfere with this process.

**Hint**: Consider how substituents on the benzene ring can affect the availability of the lone pair on nitrogen.

### Step 2: Understanding the Reason
The reason states that "it is due to steric hindrance because of the solvation of cation."
- **Explanation**: The ortho substituents can create steric hindrance, making it difficult for the nitrogen to effectively bond with protons. Additionally, when the aniline is protonated, the resulting cation can be sterically hindered by the ortho substituents, further decreasing the basicity.

**Hint**: Think about how the spatial arrangement of atoms can affect chemical interactions, especially in protonation.

### Step 3: Analyzing the Relationship Between Assertion and Reason
We need to determine if the reason provided correctly explains the assertion.
- **Explanation**: The assertion is true as the ortho effect indeed leads to a decrease in the basicity of aniline. The reason is also true because steric hindrance plays a significant role in this decrease. Therefore, the reason does provide a correct explanation for the assertion.

**Hint**: Reflect on whether the steric hindrance mentioned in the reason directly relates to the decrease in basicity stated in the assertion.

### Step 4: Conclusion
Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is that the assertion is true, the reason is true, and the reason is the correct explanation for the assertion.

**Final Answer**: The assertion is true, the reason is true, and the reason is the correct explanation for the assertion.