A : The dehydration of ethyl alcohol in presence of `Al_(2)O_(3)` at 633 K gives ethene.
R : The reaction proceed through the formation of carbocation intermediate.

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 both the assertion (A) and the reason (R) provided in the question.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that the dehydration of ethyl alcohol (C2H5OH) in the presence of Al2O3 at 633 K gives ethene (C2H4).
- Dehydration refers to the removal of water (H2O) from the alcohol, resulting in the formation of an alkene.

2. **Chemical Reaction**:
- The chemical reaction can be represented as:
\[ \text{C}_2\text{H}_5\text{OH} \xrightarrow{\text{Al}_2\text{O}_3, 633 \text{ K}} \text{C}_2\text{H}_4 + \text{H}_2\text{O} \]
- This indicates that ethyl alcohol loses a water molecule to form ethene.

3. **Understanding the Reason (R)**:
- The reason states that the reaction proceeds through the formation of a carbocation intermediate.
- A carbocation is a positively charged carbon species that forms during the reaction mechanism.

4. **Mechanism of Dehydration**:
- When ethyl alcohol is heated with Al2O3, the hydroxyl group (-OH) is removed, leading to the formation of a carbocation:
\[ \text{C}_2\text{H}_5\text{OH} \rightarrow \text{C}_2\text{H}_5^+ + \text{H}_2\text{O} \]
- The carbocation (C2H5+) is then unstable and can lose a hydrogen atom to form ethene:
\[ \text{C}_2\text{H}_5^+ \rightarrow \text{C}_2\text{H}_4 + \text{H}^+ \]

5. **Conclusion**:
- Both the assertion and the reason are correct. The dehydration of ethyl alcohol does yield ethene, and this reaction indeed proceeds through a carbocation intermediate.

### Final Answer:
Both A and R are correct, and R is the correct explanation of A.