An alcohol, on dehydration produces an alkene which on ozonolysis yields two molecules of ethanal. The alcohol is, therefore.

Options

A. `CH_(3)CH_(2)CH_(2)OH`
B. `CH_(3)CH_(2)OH`
C. `CH_(3)-underset(CH_(3))underset(|)(C)H-CH_(2)OH`
D. `CH_(3)CH_(2)-underset(OH)underset(|)(C)H-CH_(3)`

Answer

To solve the problem step by step, we need to identify the alcohol that, upon dehydration, produces an alkene which then undergoes ozonolysis to yield two molecules of ethanal (acetaldehyde).

### Step 1: Understand the Products
We know that ozonolysis of the alkene yields two molecules of ethanal (CH₃CHO). This means that the alkene must be structured in such a way that when it is cleaved by ozone, it produces two molecules of ethanal.

### Step 2: Identify the Structure of Ethanal
Ethanal (acetaldehyde) has the formula CH₃CHO. Therefore, we need to consider how two molecules of this compound can be formed from an alkene.

### Step 3: Determine the Alkene Structure
To produce two ethanal molecules from an alkene, the alkene must be butene (C₄H₈). The ozonolysis of butene can yield two ethanal molecules.

### Step 4: Identify the Alcohol
Now, we need to find an alcohol that can dehydrate to form butene. The most straightforward candidate is 2-butanol (C₄H₁₀O), which is a secondary alcohol.

### Step 5: Dehydration Reaction
When 2-butanol undergoes dehydration (removal of water), it forms butene (specifically, 2-butene). The reaction can be represented as follows:

\[ \text{C}_4\text{H}_{10}\text{O} \xrightarrow{\text{H}^+} \text{C}_4\text{H}_8 + \text{H}_2\text{O} \]

### Step 6: Ozonolysis of Butene
The ozonolysis of 2-butene will yield two molecules of ethanal:

\[ \text{C}_4\text{H}_8 + \text{O}_3 \rightarrow 2 \text{C}_2\text{H}_4\text{O} \]

### Conclusion
Thus, the alcohol that upon dehydration produces an alkene which on ozonolysis yields two molecules of ethanal is **2-butanol**.

### Final Answer
The alcohol is **2-butanol**.

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