Read the passage given below and answer the following questions:
Aldehydes, ketones and carboxylic acids are few of the major classes of organic compounds containing carbonyl group. Aldehydes are prepared by dehydrogenation or controlled oxidation of primary alcohols and controlled or selective reduction of acyl halides. Ketones are prepared by oxidation of secondary alcohols and hydration of alkynes. Carboxylic acids are prepared by the oxidation of primary alcohols, aldehydes and alkenes by hydrolysis of nitriles and by treatment of Grignard reagents with carbon dioxide.
Name the main compounds A and B formed in the following reaction:
` CH_3CN underset((ii) H_2O^(+) ) overset( (i) CH_3MgBr) to A overset( Zn( Hg) //conc. HCl) to B `

Options

A. ` CH_3CH_2COOH[A],CH_3CH_2CH_3[B]`
B. ` CH_3CH_2CHO[A],C_2H_4[B]`
C. ` CH_3COCH_3[A],CH_3CH_2CH_3[B]`
D. ` CH_3COCH_3[A],C_2H_6[B]`

Explanation

To solve the question, we will analyze the reaction step by step and identify the compounds A and B formed in the process.

### Step 1: Identify Compound A
The reaction begins with methyl cyanide (CH₃CN), which is also known as acetonitrile. When the Grignard reagent (CH₃MgBr) is added to acetonitrile, the nucleophilic methyl group from the Grignard reagent attacks the electrophilic carbon of the cyanide group.

1. **Reaction of Methyl Cyanide with Grignard Reagent**:
- CH₃CN + CH₃MgBr → CH₃C(=N)CH₃ (intermediate)
- The carbon in the cyanide group (C≡N) is electrophilic, and the nucleophilic methyl group from the Grignard reagent attacks it, leading to the formation of an intermediate.

2. **Hydrolysis of the Intermediate**:
- On hydrolysis (addition of water), the carbon-nitrogen bond is broken, and we get a ketone.
- CH₃C(=N)CH₃ + H₂O → CH₃C(=O)CH₃ + NH₃
- The product formed here is acetone (CH₃COCH₃), which is a ketone.

Thus, **Compound A is Acetone (CH₃COCH₃)**.

### Step 2: Identify Compound B
The next step involves the reduction of Compound A (acetone) using zinc amalgam and concentrated hydrochloric acid (HCl). This is known as the Clemmensen reduction.

1. **Clemmensen Reduction**:
- CH₃COCH₃ + Zn(Hg) + HCl → C₃H₈ (propane)
- In this reaction, the carbonyl group (C=O) in acetone is reduced to a methylene group (–CH₂–) by replacing the oxygen with two hydrogen atoms.

Thus, **Compound B is Propane (C₃H₈)**.

### Final Answer:
- **Compound A**: Acetone (CH₃COCH₃)
- **Compound B**: Propane (C₃H₈)

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