Assertion: Enol form of cyclohexane-`1,3,5`-trione is more stable than its keto-form.
Reason: It does not contain a-hydrogen atoms.

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 and the reason is the correct explanations of the assertion
C. If assertion is true but reason is false.
D. If assertion is false but reason is true.

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that the enol form of cyclohexane-1,3,5-trione is more stable than its keto form.

**Hint:** Consider the general stability of keto and enol forms in organic compounds.

### Step 2: Analyze the Structure of Cyclohexane-1,3,5-trione
Cyclohexane-1,3,5-trione has three carbonyl (C=O) groups located at positions 1, 3, and 5 of the cyclohexane ring.

**Hint:** Draw the structure of cyclohexane-1,3,5-trione to visualize the carbonyl groups and their positions.

### Step 3: Consider the Enol Form
The enol form of cyclohexane-1,3,5-trione would involve the conversion of one of the carbonyl groups to an alcohol (C-OH) group.

**Hint:** Remember that enolization involves the presence of alpha hydrogen atoms for stability.

### Step 4: Evaluate Stability
Keto forms are generally more stable than enol forms because of the stronger C=O double bond compared to the C-OH bond in enols. In this case, the assertion that the enol form is more stable is incorrect.

**Hint:** Recall that keto-enol tautomerism favors the keto form due to the stability of carbonyl groups.

### Step 5: Analyze the Reason
The reason states that the enol form does not contain alpha-hydrogen atoms. This is true, as the carbonyl groups in cyclohexane-1,3,5-trione do not have any hydrogen atoms attached to the carbon adjacent to them.

**Hint:** Consider the role of alpha-hydrogens in the stability of enol forms.

### Step 6: Conclusion
Since the assertion is false (the enol form is not more stable than the keto form) but the reason is true (there are no alpha-hydrogens), the correct answer is that the assertion is false and the reason is true.

**Final Answer:** D) Assertion is false, but reason is true.