In which of the following reaction the final product is neither an acid nor an acid salt.

Options

A. `Ph-CHO overset("Tollen's reagent ")to`
B. `CH_(3)-CH_(2)-OH overset(KMnO_(4)//overset(-)(O)H) to`
C. `Ph-CHO overset("Fehling reagent ")to`
D. `Ph-CHO overset(K_(2)Cr_(2)O_(7)//H^(-))to`

Answer

To solve the question of which reaction results in a final product that is neither an acid nor an acid salt, we will analyze each given reaction step by step.

### Step 1: Analyze the first reaction
**Reaction:** Benzaldehyde (C₆H₅CHO) in the presence of Tollen's reagent (Ag(NH₃)₂OH).

- **Expected Product:** When benzaldehyde reacts with Tollen's reagent, it is oxidized to form benzoic acid (C₆H₅COOH).
- **Conclusion:** The final product is benzoic acid, which is an acid. Thus, this option is incorrect.

### Step 2: Analyze the second reaction
**Reaction:** Ethanol (C₂H₅OH) in the presence of KMnO₄.

- **Expected Product:** Ethanol is oxidized by KMnO₄ to form acetic acid (C₂H₅COOH) and potassium acetate (C₂H₅COOK).
- **Conclusion:** The final product includes acetic acid, which is an acid, and potassium acetate, which is an acid salt. Thus, this option is also incorrect.

### Step 3: Analyze the third reaction
**Reaction:** Benzaldehyde (C₆H₅CHO) in the presence of Fehling's reagent.

- **Expected Product:** Benzaldehyde lacks an alpha hydrogen, which means it cannot form an enolate ion. Therefore, it does not react with Fehling's reagent under normal conditions.
- **Conclusion:** Since there is no reaction, there is no formation of an acid or an acid salt. Thus, this option is correct.

### Step 4: Analyze the fourth reaction
**Reaction:** Benzaldehyde (C₆H₅CHO) in the presence of K₂Cr₂O₇ and H⁺.

- **Expected Product:** Benzaldehyde is oxidized to benzoic acid (C₆H₅COOH) in the presence of K₂Cr₂O₇.
- **Conclusion:** The final product is benzoic acid, which is an acid. Thus, this option is incorrect.

### Final Conclusion
The only reaction where the final product is neither an acid nor an acid salt is the third reaction involving benzaldehyde and Fehling's reagent.

**Correct Answer:** C (Benzaldehyde in the presence of Fehling's reagent)

---