An organic compound (X) with molecular formula `C_(9)H_(10)O` gives positive 2, 4-DNP and Tollens'tests. It undergoes Cannizzaro reaction and on vigorous oxidation it gives 1, 4-benzenedicarboxylic acid. Compound (X) is

Options

A. Benzaldehyde
B. o-methylbenzaldehyde
C. p-ethylbenzaldehyde
D. 2, 2-dimethylhexanal.

Explanation

To determine the structure of the organic compound (X) with the molecular formula C9H10O, we will analyze the information given step by step.

### Step 1: Calculate the Unsaturation Number
The unsaturation number (or degree of unsaturation) can be calculated using the formula:
\[ \text{Unsaturation Factor} = \frac{2C + 2 - H - X}{2} \]
Where:
- C = number of carbon atoms
- H = number of hydrogen atoms
- X = number of halogen atoms (which is 0 in this case)

For the compound C9H10O:
- C = 9
- H = 10
- O = 1 (not counted in the formula)

Substituting these values into the formula:
\[ \text{Unsaturation Factor} = \frac{2(9) + 2 - 10 - 0}{2} = \frac{18 + 2 - 10}{2} = \frac{10}{2} = 5 \]

**Hint:** The unsaturation factor indicates the presence of rings or multiple bonds. An unsaturation factor of 5 suggests a complex structure, likely containing a benzene ring and additional functional groups.

### Step 2: Analyze the Tests
The compound gives positive results for:
- 2,4-DNP test (indicating the presence of a carbonyl group, either aldehyde or ketone)
- Tollens' test (indicating the presence of an aldehyde)

Since the compound undergoes the Cannizzaro reaction, it must lack alpha hydrogen atoms, confirming it is an aldehyde.

**Hint:** The positive Tollens' test specifically indicates that the compound is an aldehyde, which helps narrow down the possibilities.

### Step 3: Identify the Structure
Given that the compound is an aldehyde and has a benzene ring, we can deduce that the structure might be a substituted benzaldehyde. The molecular formula suggests that there are additional carbon atoms beyond the benzene ring.

The structure of the compound can be represented as:
- A benzene ring (C6H5)
- An aldehyde group (CHO)
- Additional carbon atoms (C3H7)

The possible structures include:
- Para-ethylbenzaldehyde (C6H5CHO with an ethyl group at the para position)

**Hint:** The presence of the ethyl group and the benzaldehyde structure aligns with the molecular formula C9H10O.

### Step 4: Confirm the Oxidation Product
The compound undergoes vigorous oxidation to yield 1,4-benzenedicarboxylic acid. This indicates that the oxidation of the ethyl group leads to the formation of carboxylic acids.

The oxidation of para-ethylbenzaldehyde would yield:
- 1,4-benzenedicarboxylic acid (C6H4(COOH)2)

**Hint:** The oxidation product confirms that the original compound contains an ethyl group adjacent to the aldehyde, leading to the formation of the dicarboxylic acid upon oxidation.

### Conclusion
Based on the analysis, the organic compound (X) is identified as **para-ethylbenzaldehyde**.

**Final Answer:** Compound (X) is para-ethylbenzaldehyde.