Observe the following sequence of reaction and answer the questions based on it. Phenylacetylene `overset(CH_(3)MgBr)underset(-CH_(4))to x overset((i)CO_(2))underset((ii)H^(o+))to y overset(H_(2)O //H_(2)SO_(4))underset(HgSO_(4))to z overset(Delta)to w`
Which of the following statement is not correct

Options

A. y decolourises `Br_(2)//H_(2)O` solution
B. z on heating liberates `CO_(2)` gas
C. w on reaction with NaOl gives yellow ppt
D. x liberates `H_(2)` gas with Na metal

Explanation

To solve the given sequence of reactions involving phenylacetylene and identify the incorrect statement, we will analyze each step of the reaction sequence carefully.

### Step-by-Step Solution:

1. **Identify the Starting Compound:**
- The starting compound is **phenylacetylene**, which can be represented as:
\[ \text{C}_6\text{H}_5\text{C} \equiv \text{C} \text{ (Phenylacetylene)} \]

2. **Reaction with Grignard Reagent:**
- Phenylacetylene reacts with **CH₃MgBr** (a Grignard reagent). The Grignard reagent adds to the terminal alkyne, resulting in the formation of an alkynyl magnesium bromide intermediate:
\[ \text{C}_6\text{H}_5\text{C} \equiv \text{C} \text{MgBr} + \text{CH}_3\text{MgBr} \rightarrow \text{C}_6\text{H}_5\text{C}(\text{CH}_3)\text{MgBr} \]
- This intermediate then loses **CH₄** (methane) to form compound **X**:
\[ \text{X} = \text{C}_6\text{H}_5\text{C}(\text{CH}_3) \text{ (Alkylated product)} \]

3. **Reaction with Carbon Dioxide:**
- The next step involves reacting **X** with **CO₂** followed by acidification (H⁺):
\[ \text{C}_6\text{H}_5\text{C}(\text{CH}_3)\text{MgBr} + \text{CO}_2 \rightarrow \text{C}_6\text{H}_5\text{C}(\text{COOH})(\text{CH}_3) \text{ (Carboxylic acid Y)} \]
- After acidification, we obtain **Y**:
\[ \text{Y} = \text{C}_6\text{H}_5\text{C}(\text{COOH})(\text{CH}_3) \]

4. **Hydration and Kucherov Reaction:**
- **Y** is then treated with **H₂O**, **H₂SO₄**, and **HgSO₄** (Kucherov reagent):
\[ \text{C}_6\text{H}_5\text{C}(\text{COOH})(\text{CH}_3) \rightarrow \text{C}_6\text{H}_5\text{C}(\text{C=O})(\text{CH}_3) \text{ (Ketone Z)} \]
- This results in the formation of **Z** (a ketone).

5. **Decarboxylation:**
- Heating **Z** leads to decarboxylation:
\[ \text{C}_6\text{H}_5\text{C}(\text{C=O})(\text{CH}_3) \xrightarrow{\Delta} \text{C}_6\text{H}_5\text{C}(\text{CH}_3) + \text{CO}_2 \text{ (Final product W)} \]
- The final product **W** is:
\[ \text{W} = \text{C}_6\text{H}_5\text{C}(\text{CH}_3) \]

### Evaluation of Statements:

1. **Statement 1:** Y decolorizes Br₂/H₂O solution.
- **Correct:** Y contains a double bond (unsaturation).

2. **Statement 2:** Z on heating liberates CO₂.
- **Correct:** Z undergoes decarboxylation upon heating.

3. **Statement 3:** W on reaction with NaOI gives yellow PPT.
- **Correct:** W can undergo a haloform reaction due to the presence of a methyl ketone.

4. **Statement 4:** X liberates hydrogen gas with Na metal.
- **Incorrect:** X does not have an active hydrogen (attached to an oxygen) to liberate H₂ with Na.

### Conclusion:
The statement that is **not correct** is the fourth statement: "X liberates hydrogen gas with Na metal."