Which of the following is not obtained by the reaction between ethanol and concentrated `H_(2)SO_(4)` under any conditions?

Options

A. `C_(2)H_(4)`
B. `CH_(3)CHO`
C. `CH_(3)CH_(2)OCH_(2)CH_(3)`
D. `CH_(3)CH_(2)HSO_(4)`

Explanation

To solve the question "Which of the following is not obtained by the reaction between ethanol and concentrated H₂SO₄ under any conditions?", we need to analyze the possible reactions that can occur between ethanol (C₂H₅OH) and concentrated sulfuric acid (H₂SO₄).

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants are ethanol (C₂H₅OH) and concentrated sulfuric acid (H₂SO₄).

2. **Understand the Role of Sulfuric Acid**:
- Sulfuric acid acts as a strong acid and can protonate the hydroxyl group (-OH) of ethanol, making it a better leaving group.

3. **Formation of Carbocation**:
- When ethanol is treated with concentrated H₂SO₄, the -OH group can be protonated to form water (H₂O), leading to the formation of a carbocation (C₂H₅⁺).

4. **Possible Reactions**:
- **Elimination Reaction**: The carbocation can lose a proton (H⁺) to form ethylene (C₂H₄) through an elimination reaction.
- **Substitution Reaction**: The carbocation can also react with another ethanol molecule to form an ether (C₂H₅OC₂H₅).
- **Formation of Alkyl Hydrogen Sulfate**: The carbocation can react with the bisulfate ion (HSO₄⁻) to form ethyl hydrogen sulfate (C₂H₅OSO₃H).

5. **Identify the Products**:
- The products that can be formed from the reactions mentioned above include:
- Ethylene (C₂H₄)
- Ethyl hydrogen sulfate (C₂H₅OSO₃H)
- Ether (C₂H₅OC₂H₅)

6. **Consider Oxidation**:
- It is important to note that concentrated sulfuric acid is not an oxidizing agent. Therefore, it cannot oxidize ethanol to form aldehydes or carboxylic acids.

7. **Conclusion**:
- Since oxidation is not possible with concentrated sulfuric acid, products such as aldehydes (e.g., acetaldehyde) or carboxylic acids (e.g., acetic acid) cannot be formed from the reaction of ethanol with concentrated sulfuric acid.

### Final Answer:
The product that is **not obtained** by the reaction between ethanol and concentrated H₂SO₄ under any conditions is **aldehyde or carboxylic acid**.