Identify the final product in that follow sequence of reactions.
`CH_(2)=CH_(2)overset(Br_(2))rarr(X)overset(KCN)rarr (Y) overset(H_(3)O^(+))rarr (Z)`

Options

A. `CH_(3)BrCH_(2)COOH`
B. `HOOC CH_(2)COOH`
C. `HOOC CH_(2)CH_(2)COOH`
D. `HOOC CH(CH_(3))COOH`

Answer

To solve the problem step by step, let's analyze the sequence of reactions given:

1. **Starting Compound**: The reaction starts with ethene (CH₂=CH₂).

2. **First Reaction**: Ethene reacts with bromine (Br₂).
- Ethene undergoes electrophilic addition with bromine, resulting in the formation of 1,2-dibromoethane (X).
- The reaction can be represented as:
\[ CH_2=CH_2 + Br_2 \rightarrow CH_2Br-CH_2Br \]
- **Product X**: 1,2-dibromoethane (C₂H₄Br₂).

3. **Second Reaction**: The dibromo compound (X) reacts with potassium cyanide (KCN).
- In this step, KCN acts as a nucleophile and replaces the bromine atoms with cyanide groups. This reaction typically results in the formation of a dinitrile.
- The reaction can be represented as:
\[ CH_2Br-CH_2Br + 2 KCN \rightarrow CH_2(CN)-CH_2(CN) \]
- **Product Y**: 1,2-dicyanoethane (C₂H₂(CN)₂).

4. **Third Reaction**: The dicyano compound (Y) is treated with hydronium ion (H₃O⁺).
- In an acidic medium, the nitrile groups undergo hydrolysis to form carboxylic acids. Each cyanide group (CN) is converted to a carboxylic acid (COOH).
- The reaction can be represented as:
\[ CH_2(CN)-CH_2(CN) + 2 H_3O^+ \rightarrow CH_2(COOH)-CH_2(COOH) \]
- **Product Z**: 1,2-ethanedioic acid (also known as oxalic acid, C₂H₂O₄).

Thus, the final product (Z) after the sequence of reactions is **1,2-ethanedioic acid (oxalic acid)**.

### Summary of Products:
- **X**: 1,2-dibromoethane (C₂H₄Br₂)
- **Y**: 1,2-dicyanoethane (C₂H₂(CN)₂)
- **Z**: 1,2-ethanedioic acid (C₂H₂O₄)

### Final Answer:
The final product Z is **1,2-ethanedioic acid (oxalic acid)**.

---