Chain-growth polymerization may proceed by the following mechanism

Options

A. Free radical polymerization
B. Cantionic polymerization
C. Anionic polymerization
D. None of the above

Explanation

To solve the question regarding the mechanisms by which chain-growth polymerization may proceed, we will analyze each option provided and determine which ones are valid mechanisms.

### Step-by-Step Solution:

1. **Understanding Chain-Growth Polymerization**:
- Chain-growth polymerization is a process where monomeric units with double or triple bonds are added together to form a polymer. This process involves the repeated addition of these monomers to form long chains.

2. **Identifying the Mechanisms**:
- The question provides four options:
- (a) Free Radical Polymerization
- (b) Cationic Polymerization
- (c) Anionic Polymerization
- (d) Non-additive

3. **Analyzing Each Option**:
- **Option (a): Free Radical Polymerization**:
- This is a common mechanism for chain-growth polymerization. It involves the initiation of polymerization by free radicals, which can add to the double bonds of the monomers, leading to chain growth.
- **Option (b): Cationic Polymerization**:
- This mechanism involves the initiation of polymerization by cations. Similar to free radical polymerization, cationic polymerization allows for the addition of monomers to form a polymer chain.
- **Option (c): Anionic Polymerization**:
- Anionic polymerization is another valid mechanism where the initiation is done by anions. This method also leads to the chain growth of polymers.
- **Option (d): Non-additive**:
- This option is not a mechanism of chain-growth polymerization. Non-additive processes do not involve the addition of monomers to form long chains.

4. **Conclusion**:
- The mechanisms that can proceed by chain-growth polymerization are Free Radical Polymerization, Cationic Polymerization, and Anionic Polymerization. Therefore, the correct answer includes the first three options.

### Final Answer:
Chain-growth polymerization may proceed by:
- Free Radical Polymerization
- Cationic Polymerization
- Anionic Polymerization