`3CH_3 COCH_3 overset(HCl)to (CH_3)_2 C =CH -CO -CH =C(CH_3)_2`
This polymer (B) is obtained when acetone is saturated with hydrogen chloride gas, B can be

Options

A. Phorone
B. Formose
C. Diacetone alcohol
D. Mesityl oxide

Explanation

To solve the problem, we need to understand the reaction of acetone (CH₃COCH₃) when it is treated with hydrogen chloride (HCl). The reaction leads to the formation of a polymer, which we will denote as compound B.

### Step-by-Step Solution:

1. **Identify the Reactant**:
The reactant is acetone, which has the chemical formula CH₃COCH₃.

2. **Understand the Reaction Conditions**:
The reaction occurs in the presence of hydrogen chloride gas (HCl). This suggests that the acetone molecules will undergo a polymerization reaction facilitated by HCl.

3. **Polymerization Mechanism**:
When acetone is saturated with HCl, the hydrogen chloride can protonate the carbonyl oxygen of acetone, making it more electrophilic. This allows the acetone molecules to react with each other, leading to the formation of larger molecules.

4. **Formation of Compound B**:
The polymerization of acetone leads to the formation of a compound with multiple acetone units. Specifically, the reaction can lead to the formation of a compound with double bonds and branching due to the nature of the acetone structure.

5. **Identify the Structure of Compound B**:
The resulting compound B can be represented as (CH₃)₂C=CH-CO-CH= C(CH₃)₂. This structure indicates that we have a polymer with a backbone of carbon atoms, including double bonds and methyl groups.

6. **Conclusion**:
The polymer formed from the reaction of three acetone molecules in the presence of HCl is a compound known as 4-on, which has the structure (CH₃)₂C=CH-CO-CH=C(CH₃)₂.

### Final Answer:
The polymer (B) obtained from the reaction of acetone with hydrogen chloride is (CH₃)₂C=CH-CO-CH=C(CH₃)₂, also known as 4-on.

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