Which of the following set is correct :
Compound Positive test of
`{:((a)CH_(3)CHO,,,,"Fehling test"),((b)Ph-CHO,,,,"Tollen's reagent"),((c )HCOOH,,,,"Benedict solution"),((d)Ph-CHO,,,,"Fehling solution"),((e)CH_(3)COCH_(3),,,,"Tollen's reagent"):}`

Options

A. a, b, c, d
B. a, b, c
C. a, b, d, e
D. All

Answer

To determine which of the given compounds gives a positive test for the specified reagents, we will analyze each compound and its corresponding test step by step.

### Step 1: Analyze Compound A (CH₃CHO) with Fehling's Test
- **Fehling's Test** is used to detect aldehydes. For a positive test, the aldehyde must have at least one hydrogen atom attached to the carbon adjacent to the carbonyl group (CHO).
- **CH₃CHO** (acetaldehyde) has the structure:
```
H
|
H-C=O
|
H
```
- It has a hydrogen atom attached to the carbon adjacent to the carbonyl group.
- **Conclusion**: Positive test for Fehling's Test.

### Step 2: Analyze Compound B (Ph-CHO) with Tollen's Reagent
- **Tollen's Reagent** is also used to detect aldehydes. It does not require the adjacent carbon to have a hydrogen atom.
- **Ph-CHO** (benzaldehyde) has the structure:
```
O
||
Ph-C
```
- Benzaldehyde does not have any hydrogen on the carbon adjacent to the carbonyl group, but it is still an aldehyde.
- **Conclusion**: Positive test for Tollen's Reagent.

### Step 3: Analyze Compound C (HCOOH) with Benedict's Solution
- **Benedict's Solution** is used to test for reducing sugars and aldehydes. It can also give a positive test for carboxylic acids under certain conditions.
- **HCOOH** (formic acid) has the structure:
```
O
||
H-C-OH
```
- Formic acid can release CO₂ and thus can show a positive test.
- **Conclusion**: Positive test for Benedict's Solution.

### Step 4: Analyze Compound D (Ph-CHO) with Fehling's Solution
- We already established that **Ph-CHO** (benzaldehyde) is an aldehyde.
- However, since it does not have a hydrogen atom adjacent to the carbonyl group, it will not give a positive test with Fehling's solution.
- **Conclusion**: Negative test for Fehling's Solution.

### Step 5: Analyze Compound E (CH₃COCH₃) with Tollen's Reagent
- **CH₃COCH₃** (acetone) is a ketone.
- Ketones do not give a positive test with Tollen's reagent, which is specific for aldehydes.
- **Conclusion**: Negative test for Tollen's Reagent.

### Final Summary
- **Compound A (CH₃CHO)**: Positive for Fehling's Test.
- **Compound B (Ph-CHO)**: Positive for Tollen's Reagent.
- **Compound C (HCOOH)**: Positive for Benedict's Solution.
- **Compound D (Ph-CHO)**: Negative for Fehling's Solution.
- **Compound E (CH₃COCH₃)**: Negative for Tollen's Reagent.

### Correct Set of Positive Tests
The correct set of compounds that give positive tests is:
- (a) CH₃CHO with Fehling's Test
- (b) Ph-CHO with Tollen's Reagent
- (c) HCOOH with Benedict's Solution

Thus, the correct answer is **(a), (b), (c)**.

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