`CH_3COOH overset(Br_2//P) rarr (Y) overset((i) KCN) underset((ii) H_3 O^+)rarr (X)`
Here, `(X)` is :

Options

A. Glycollic acid
B. `alpha`-Hydroxypropionic acid
C. Succinic acid
D. Malonic acid

Explanation

To solve the question step by step, we will analyze the reactions involving acetic acid (CH₃COOH) and the reagents provided.

### Step 1: Reaction of Acetic Acid with Bromine and Phosphorus

1. **Starting Material**: Acetic acid (CH₃COOH).
2. **Reagents**: Bromine (Br₂) and Phosphorus (P).
3. **Reaction Type**: This is a halogenation reaction where acetic acid undergoes bromination.
4. **Product Formation**: The bromination occurs at the alpha position (the carbon adjacent to the carboxylic acid group), resulting in the formation of 2-bromopropanoic acid (BrCH₂COOH).

**Product (Y)**: BrCH₂COOH

### Step 2: Reaction of Product Y with KCN

1. **Starting Material**: 2-bromopropanoic acid (BrCH₂COOH).
2. **Reagents**: Potassium cyanide (KCN) in alcoholic solution.
3. **Reaction Type**: Nucleophilic substitution reaction (S_N2) occurs here, where the cyanide ion (CN⁻) acts as a nucleophile and replaces the bromine atom.
4. **Product Formation**: The product formed is 2-cyanoacetic acid (CNCH₂COOH).

**Intermediate Product**: CNCH₂COOH

### Step 3: Hydrolysis of the Intermediate Product

1. **Starting Material**: 2-cyanoacetic acid (CNCH₂COOH).
2. **Reagents**: Acidic hydrolysis using H₃O⁺ (hydronium ion).
3. **Reaction Type**: The cyano group (CN) undergoes hydrolysis to form a carboxylic acid.
4. **Product Formation**: The hydrolysis of the cyano group leads to the formation of malonic acid (HOOC-CH₂-COOH).

**Final Product (X)**: Malonic acid (HOOC-CH₂-COOH)

### Conclusion

The final product (X) after the complete reaction sequence is malonic acid.

**Answer**: (X) is malonic acid.

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