An organic compound 'X' having molecular formula `C_(5)H_(10)O` yield phenylhydrazone and gives negative response to the iodoform test and Tollens test . It produces n-pentane on reduction. 'X' could be

Options

A. n-amyl alcohol
B. Pentanal
C. 2-pentanone
D. 3-pentanone

Answer

To solve the problem, we need to identify the organic compound 'X' with the molecular formula \( C_5H_{10}O \) based on the given clues. Let's break down the information step by step.

### Step 1: Analyze the molecular formula
The molecular formula \( C_5H_{10}O \) indicates that the compound could be an alcohol, aldehyde, or ketone.

### Step 2: Identify the tests and their implications
1. **Phenylhydrazone Formation**: The compound can yield a phenylhydrazone, which typically indicates that the compound is a ketone or an aldehyde.
2. **Negative Iodoform Test**: The Iodoform test is positive for compounds with the structure \( RCOCH_3 \) (methyl ketones) or \( RCHOHCH_3 \) (secondary alcohols). A negative result means that 'X' does not have a methyl ketone or a secondary alcohol structure.
3. **Negative Tollens Test**: The Tollens test is positive for aldehydes. A negative result indicates that 'X' is not an aldehyde.
4. **Produces n-pentane on reduction**: This suggests that 'X' is likely a ketone, as ketones can be reduced to alkanes.

### Step 3: Evaluate the options
Now, let's evaluate the given options based on the above information:

1. **n-Amyl alcohol (Pentanol)**:
- Structure: \( CH_3(CH_2)_4OH \)
- Negative for both tests, but does not yield phenylhydrazone (alcohol).

2. **Pentanal (Aldehyde)**:
- Structure: \( CH_3(CH_2)_3CHO \)
- Positive for Tollens test (not suitable).

3. **2-Pentanone**:
- Structure: \( CH_3CH_2C(=O)CH_2CH_3 \)
- Positive for Iodoform test (not suitable).

4. **3-Pentanone**:
- Structure: \( CH_3CH_2C(=O)CH_2CH_3 \)
- Negative for both tests and can yield phenylhydrazone.

### Step 4: Confirm the correct option
- **3-Pentanone** fits all criteria:
- It yields phenylhydrazone.
- It gives negative responses to both the Iodoform and Tollens tests.
- It can be reduced to n-pentane.

### Conclusion
The correct answer is **3-Pentanone**.

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