End product of the following sequence of reactions is
`CH-=CH overset(CH_(3)MgBr)to overset(HgSO_(4)//H_(2)SO_(4))to underset(Delta)overset(Ag_(2)O)to`

Options

A. `CH_(3)-underset(H)underset(|)overset(OH)overset("||")C-COOH`
B. `CH_(2)(COOH)_(2)`
C. `OHC-CH_(2)-COOH`
D. `H-overset(O)overset("||")C-CH_(2)COOH`

Explanation

To determine the end product of the given sequence of reactions, we will go through each step systematically.

### Step 1: Reaction of Acetylene with Grignard Reagent
The starting compound is acetylene (CH≡CH). When acetylene reacts with the Grignard reagent (CH₃MgBr), the nucleophilic carbon from the Grignard reagent attacks one of the carbon atoms of the acetylene, leading to the formation of a new carbon-carbon bond.

**Reaction:**
\[ \text{CH} \equiv \text{CH} + \text{CH}_3\text{MgBr} \rightarrow \text{CH} \equiv \text{C} - \text{C}(\text{CH}_3) - \text{MgBr} \]

This results in the formation of a magnesium alkynyl compound (propyne) and methane (CH₄) as a byproduct.

### Step 2: Reaction with Carbon Dioxide
Next, the magnesium alkynyl compound reacts with carbon dioxide (CO₂) in the presence of an acid (H⁺ or H₃O⁺). The negatively charged carbon from the alkynyl compound attacks the carbon of CO₂, forming a carboxylic acid.

**Reaction:**
\[ \text{CH} \equiv \text{C} - \text{C}(\text{CH}_3) - \text{MgBr} + \text{CO}_2 \rightarrow \text{CH} \equiv \text{C} - \text{C}(\text{CH}_3) - \text{COOH} \]

This results in the formation of a carboxylic acid (2-methylpropenoic acid).

### Step 3: Hydration with HgSO₄ and H₂SO₄
The next step involves the hydration of the alkyne using mercuric sulfate (HgSO₄) and sulfuric acid (H₂SO₄). This reaction leads to the formation of an enol, which can undergo keto-enol tautomerism.

**Reaction:**
\[ \text{CH} \equiv \text{C} - \text{C}(\text{CH}_3) - \text{COOH} \xrightarrow{\text{HgSO}_4, \text{H}_2\text{SO}_4} \text{CH}_3\text{C}(OH)=\text{C}(\text{COOH}) \]

This results in the formation of an enol which can tautomerize to form a ketone.

### Step 4: Tautomerization
The enol formed can tautomerize to a ketone, leading to the formation of a more stable structure.

**Tautomerization:**
\[ \text{CH}_3\text{C}(OH)=\text{C}(\text{COOH}) \rightleftharpoons \text{CH}_3\text{C}=\text{C}(\text{COOH}) \]

### Step 5: Oxidation with Ag₂O
Finally, the ketone undergoes oxidation with silver oxide (Ag₂O), which is a mild oxidizing agent. This oxidation converts the aldehyde group to a carboxylic acid.

**Reaction:**
\[ \text{CH}_3\text{C}=\text{C}(\text{COOH}) + \text{Ag}_2\text{O} \rightarrow \text{CH}_2(\text{COOH})_2 \]

This results in the formation of malic acid (CH₂(COOH)₂).

### Final Product
The end product of the sequence of reactions is malic acid, represented as:
\[ \text{CH}_2(\text{COOH})_2 \]