Compounds A and C in the following reaction are
`CH_(3)CHOunderset((ii)H_(2)O)overset((i)CH_(3)MgBr)toAoverset(H_(2)SO_(4).Delta)to(B)overset("Hydroboration oxidation")to(C)`

Options

A. identical
B. positional isomers
C. functional isomers
D. optical isomers.

Explanation

To solve the question regarding the compounds A and C in the given reaction, we will break down the steps involved in the transformation of the compounds.

### Step 1: Identify the starting compound
The starting compound is **acetaldehyde** (CH₃CHO). This is the first reactant in the reaction.

### Step 2: Reaction with Grignard Reagent
The Grignard reagent used is **methylmagnesium bromide (CH₃MgBr)**. In this reaction, the nucleophilic methyl group (CH₃⁻) from the Grignard reagent attacks the carbonyl carbon of acetaldehyde. This results in the formation of a **secondary alcohol**.

- **Reaction**:
\[ \text{CH}_3\text{CHO} + \text{CH}_3\text{MgBr} \rightarrow \text{A} \quad (\text{where A is CH}_3\text{CH(OH)CH}_3) \]

### Step 3: Formation of Compound A
After the reaction with the Grignard reagent, we obtain **compound A**, which is **2-butanol (CH₃CH(OH)CH₃)**.

### Step 4: Dehydration of Compound A
Next, compound A reacts with **sulfuric acid (H₂SO₄)** upon heating. The sulfuric acid protonates the alcohol group, converting it into a better leaving group (water). This leads to the elimination of water and the formation of an **alkene**.

- **Reaction**:
\[ \text{A} \xrightarrow{\text{H}_2\text{SO}_4, \Delta} \text{B} \quad (\text{where B is butene}) \]

### Step 5: Hydroboration-Oxidation of Compound B
The alkene (compound B) undergoes **hydroboration-oxidation**. This reaction involves the addition of borane (BH₃) followed by oxidation with hydrogen peroxide (H₂O₂) in a basic medium. The reaction follows the **anti-Markovnikov rule**, resulting in the formation of an alcohol.

- **Reaction**:
\[ \text{B} \xrightarrow{\text{BH}_3/\text{H}_2\text{O}_2} \text{C} \quad (\text{where C is butanol, CH}_3\text{CH}_2\text{CH}_2\text{OH}) \]

### Step 6: Identify Compound C
After hydroboration-oxidation, we obtain **compound C**, which is **1-butanol (CH₃CH₂CH₂OH)**.

### Conclusion
In summary, we have:
- **Compound A**: 2-butanol (CH₃CH(OH)CH₃)
- **Compound C**: 1-butanol (CH₃CH₂CH₂OH)

The relationship between compounds A and C is that they are **positional isomers**; they have the same molecular formula but differ in the position of the hydroxyl (-OH) group.