`CH_(3)-CH_(2)-C-=CH overset(40%H_2SO_(4))underset(1%HgSO_(4))toA overset ("isomerism")to CH_(3)- CH_(2)-underset(O)underset(||)C-CH_(3)`. Structure of ‘A’ and type of isomerism in the above reaction are respectively.

Options

A. But-1-en-2-ol,metamerism
B. But-1-cn-ol,tautomerism
C. But-2-en-2-ol,geometrical
D. But-1-en-2-ol,tautomerism.

Answer

To solve the problem, we need to determine the structure of compound 'A' formed from the reaction of 1-butyne (CH₃-CH₂-C≡CH) with dilute sulfuric acid (H₂SO₄) and mercuric sulfate (HgSO₄). After that, we will identify the type of isomerism present in the reaction.

### Step-by-step Solution:

1. **Identify the Reactant:**
The reactant is 1-butyne, which has the structure:
\[ \text{CH}_3-\text{CH}_2-\text{C} \equiv \text{CH} \]

2. **Reaction with H₂SO₄ and HgSO₄:**
When 1-butyne reacts with dilute sulfuric acid and mercuric sulfate, the reaction follows Markovnikov's rule. The mercuric ion (Hg²⁺) adds to the terminal carbon of the alkyne, forming a vinyl cation. The reaction can be represented as:
\[ \text{CH}_3-\text{CH}_2-\text{C} \equiv \text{CH} \xrightarrow{\text{H}_2\text{SO}_4, \text{HgSO}_4} \text{CH}_3-\text{CH}_2-\text{C}(Hg) \text{=CH}_2 \]

3. **Hydrolysis:**
In the presence of water, hydrolysis occurs, and the mercuric ion is replaced by a hydroxyl group (-OH). This results in the formation of:
\[ \text{CH}_3-\text{CH}_2-\text{C(OH)}=\text{CH}_2 \]
This compound is known as 2-buten-1-ol.

4. **Identify Compound 'A':**
The structure of compound 'A' is:
\[ \text{CH}_3-\text{CH}_2-\text{C(OH)}=\text{CH}_2 \]
This is 2-buten-1-ol.

5. **Identify the Isomerism:**
The type of isomerism that occurs in this reaction is **tautomerism**. Tautomerism is a special type of isomerism where the isomers (tautomers) readily interconvert, typically involving the transfer of a hydrogen atom and a shift of a double bond.

### Final Answer:
- Structure of ‘A’: **2-buten-1-ol (CH₃-CH₂-C(OH)=CH₂)**
- Type of isomerism: **Tautomerism**