Assertion: The second dissociation constant of maleic acid is greater than fumaric acid.
Reason: Higher the dissociation constant of acid more is acidic character.

Options

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

Explanation

To analyze the assertion and reason provided in the question, we need to understand the properties of maleic acid and fumaric acid, particularly their dissociation constants (Ka values) and how they relate to acidity.

### Step-by-Step Solution:

**Step 1: Identify the Structures of Maleic Acid and Fumaric Acid**
- Maleic acid is a cis-isomer with the structure: HOOC-CH=CH-COOH.
- Fumaric acid is a trans-isomer with the structure: HOOC-CH=CH-COOH.

**Hint 1:** Remember that the geometric isomerism (cis vs trans) can affect the stability of the molecules and their ability to donate protons.

**Step 2: Understand the First and Second Dissociation Constants (Ka1 and Ka2)**
- Both maleic and fumaric acids are dicarboxylic acids, meaning they can lose two protons (H+).
- The first dissociation constant (Ka1) refers to the dissociation of the first proton, while the second dissociation constant (Ka2) refers to the dissociation of the second proton.

**Hint 2:** The dissociation constant (Ka) indicates how easily an acid can donate a proton; a higher Ka value means a stronger acid.

**Step 3: Compare the First Dissociation Constants (Ka1)**
- Maleic acid has a higher Ka1 than fumaric acid. This is because the cis configuration of maleic acid allows for intramolecular hydrogen bonding, stabilizing the carboxylate ion formed after the first dissociation.

**Hint 3:** Intramolecular interactions can enhance the stability of ions formed during dissociation.

**Step 4: Compare the Second Dissociation Constants (Ka2)**
- For the second dissociation (Ka2), fumaric acid has a higher Ka2 than maleic acid. This is due to the stability of the carboxylate ion formed after the first dissociation. In fumaric acid, the trans configuration reduces steric hindrance, allowing for better stabilization of the negative charge on the carboxylate ion after the second proton is lost.

**Hint 4:** The arrangement of atoms in a molecule can affect the stability of the resulting ions after dissociation.

**Step 5: Conclusion on Assertion and Reason**
- The assertion states that the second dissociation constant of maleic acid is greater than that of fumaric acid, which is **false**.
- The reason states that a higher dissociation constant indicates a stronger acidic character, which is **true**.
- Therefore, the correct conclusion is that the assertion is false, but the reason is true.

**Final Answer:** The assertion is false, and the reason is true.