Which of the following unbalanced reactions is/are correct?

Options

A. a.
B. b.
C. c.
D.

Explanation

To determine which of the given unbalanced reactions are correct, we will analyze each reaction based on the reagents used and the nature of the organic compounds involved.

### Step-by-Step Solution:

1. **Understanding the Reagents:**
- **Tollens' Reagent:** This is an oxidizing agent that specifically reacts with aldehydes and compounds that have terminal carbonyl groups. It produces a silver mirror when a positive test occurs.
- **Fehling's Reagent:** This is also an oxidizing agent that reacts with aliphatic aldehydes and produces a red precipitate of Cu2O when a positive test occurs.

2. **Analyzing Each Reaction:**
- **Reaction A:** Involves a phenyl hydroxyl amine with Tollens' reagent.
- **Analysis:** Since phenyl hydroxyl amine can react with Tollens' reagent, and if a silver mirror is formed, this reaction is correct.

- **Reaction B:** Involves an aromatic aldehyde with Fehling's reagent.
- **Analysis:** Aromatic aldehydes do not react with Fehling's reagent. Since a red precipitate cannot form in this case, this reaction is incorrect.

- **Reaction C:** Involves a ketone with Tollens' reagent.
- **Analysis:** Ketones do not react with Tollens' reagent, as it only reacts with aldehydes and terminal carbonyl groups. Therefore, this reaction is also incorrect.

- **Reaction D:** Involves formic acid (HCOOH) with Fehling's reagent.
- **Analysis:** Formic acid is a terminal aldehyde and can react with Fehling's reagent, producing a red precipitate. Thus, this reaction is correct.

3. **Conclusion:**
- The correct reactions are:
- **Reaction A:** Correct (Tollens' reagent with phenyl hydroxyl amine)
- **Reaction D:** Correct (Fehling's reagent with formic acid)
- The incorrect reactions are:
- **Reaction B:** Incorrect (aromatic aldehyde with Fehling's reagent)
- **Reaction C:** Incorrect (ketone with Tollens' reagent)

### Final Answer:
The correct unbalanced reactions are A and D.

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