`C_(6)H_(12)O_(2)(X) overset(H_(3)O^(+))toC_(2)H_(5)CO_(2)H+C_(3)H_(7)OH`, X is

Explanation

To solve the question, we need to determine the structure of compound X (C₆H₁₂O₂) that reacts with H₃O⁺ to yield C₂H₅CO₂H (propanoic acid) and C₃H₇OH (propanol).

### Step-by-Step Solution:

1. **Identify the Reaction Type**:
- The reaction involves the formation of an acid and an alcohol from a compound (X) when treated with H₃O⁺. This suggests that X is likely an ester, as esters hydrolyze to produce carboxylic acids and alcohols in the presence of an acid catalyst.

**Hint**: Look for functional groups that can yield an acid and an alcohol upon hydrolysis.

2. **Write the General Structure of an Ester**:
- An ester has the general structure RCOOR', where R and R' are hydrocarbon chains. In this case, we need to find R and R' such that the total number of carbons is 6 (C₆H₁₂O₂).

**Hint**: Remember that the total number of carbon atoms in the ester should equal the sum of the carbon atoms in the products.

3. **Analyze the Products**:
- The products are C₂H₅CO₂H (propanoic acid) which has 3 carbons and C₃H₇OH (propanol) which has 3 carbons. Therefore, the total number of carbons in the products is 6, which matches the formula of X.

**Hint**: Count the number of carbon atoms in the products to confirm the structure of the ester.

4. **Construct the Ester Structure**:
- Since propanoic acid (C₂H₅CO₂H) has a structure of C₂H₅C(=O)OH, we can deduce that the ester must have the propanoic acid part and the alcohol part (propanol, C₃H₇OH).
- Therefore, the ester can be constructed as C₂H₅C(=O)O(C₃H₇).

**Hint**: Combine the components of the acid and alcohol to form the ester.

5. **Final Structure of X**:
- The final structure of X can be represented as:
\[ C₂H₅C(=O)O(C₃H₇) \]
- This can also be written as:
\[ C₆H₁₂O₂ \]
- Thus, the compound X is ethyl propanoate (C₂H₅COOC₃H₇).

**Hint**: Ensure the final structure matches the molecular formula given in the question.

### Conclusion:
The structure of compound X is ethyl propanoate, which can be represented as:
\[ \text{X} = C₂H₅C(=O)O(C₃H₇) \]