In the reaction
` HC -= CH underset( "dil" H_2 SO_4 ) overset( Hg SO_4) to X overset(LIAIH _4 ) to Y overset(P, Br_2) to Z,` Z is

Options

A. Ethylidene bromide
B. Ehtyl bromide
C. Bromobenzene
D. Ehtylene bromide

Explanation

To determine the compound Z in the given reaction sequence, we will break down each step of the reaction process.

### Step 1: Reaction of Acetylene with Dilute H2SO4 and HgSO4
- We start with acetylene (HC≡CH).
- When acetylene reacts with dilute sulfuric acid (H2SO4) in the presence of mercuric sulfate (HgSO4), it undergoes hydration.
- According to Markovnikov's rule, water (H2O) adds across the triple bond, resulting in the formation of acetaldehyde (CH3CHO).
- **X = CH3CHO (Acetaldehyde)**

### Step 2: Reduction of Acetaldehyde with LiAlH4
- The next step involves the reduction of acetaldehyde (X) using lithium aluminum hydride (LiAlH4).
- LiAlH4 is a strong reducing agent that reduces aldehydes to primary alcohols.
- The reaction converts acetaldehyde (CH3CHO) to ethanol (CH3CH2OH).
- **Y = CH3CH2OH (Ethanol)**

### Step 3: Reaction of Ethanol with PBr2
- The final step involves the reaction of ethanol (Y) with phosphorus tribromide (PBr2).
- Ethanol is a primary alcohol, and when it reacts with PBr2, it undergoes an SN2 reaction mechanism.
- In this reaction, the hydroxyl group (OH) is replaced by a bromine atom (Br), resulting in the formation of bromoethane (CH3CH2Br).
- **Z = CH3CH2Br (Bromoethane)**

### Final Answer
Thus, the compound Z is **Bromoethane (CH3CH2Br)**.

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