The major product (H) in the given reaction sequence is :
`CH_3-CH_2-CO-CH_3overset(HCN)to Gunderset("Heat")overset(95% H_2SO_4)toH`

Options

A. `CH_3-CH=undersetunderset(CH_3)(|)C-COOH`
B. `CH_3-CH=undersetunderset(CH_3)(|)C-CN`
C. `CH_3-CH_2-undersetunderset(CH_3)(|)oversetoverset(OH)(|)C-COOH`
D. `CH_3-CH=undersetunderset(CH_3)(|)C-CO-NH_2`

Answer

To solve the problem, we will analyze the reaction sequence step by step.

### Step 1: Identify the starting material
The starting material is **CH₃-CH₂-CO-CH₃** (butan-2-one).

### Step 2: Reaction with HCN
When butan-2-one is treated with HCN (hydrogen cyanide), it undergoes a nucleophilic addition reaction. The carbonyl carbon of the ketone is electrophilic and reacts with the nucleophilic cyanide ion (CN⁻) from HCN. This results in the formation of a cyanohydrin.

**Product G:** The product formed is **CH₃-CH₂-C(OH)(CN)-CH₃** (2-hydroxy-2-methylbutanenitrile).

### Step 3: Treatment with 95% H₂SO₄
Next, the cyanohydrin (Product G) is treated with concentrated sulfuric acid (95% H₂SO₄). This step involves hydrolysis of the nitrile group (CN) to form a carboxylic acid (COOH).

During this reaction, the cyanide group is converted to a carboxylic acid, and the hydroxyl group remains intact.

**Intermediate Product:** The resulting product after hydrolysis is **CH₃-CH₂-C(OH)-COOH** (2-hydroxybutanoic acid).

### Step 4: Heating the product
Upon heating, dehydration occurs. The hydroxyl group (OH) and a hydrogen atom from the adjacent carbon can be eliminated, leading to the formation of a double bond (alkene).

This results in the formation of an unsaturated carboxylic acid.

**Final Product H:** The final product after dehydration is **CH₃-CH₂-C=CH-COOH** (butenoic acid).

### Conclusion
The major product (H) in the given reaction sequence is **CH₃-CH₂-C=CH-COOH**.

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