`CH_2 = CH_2 ` is

Options

A. monomer
B. polymer
C. isomer
D. epimer

Explanation

To determine what CH₂=CH₂ is, we can analyze the question step by step.

### Step 1: Identify the Compound
The compound CH₂=CH₂ is known as ethene (or ethylene). It consists of two carbon atoms connected by a double bond, with each carbon atom bonded to two hydrogen atoms.

### Step 2: Define the Terms
We need to understand the terms mentioned in the question:
- **Monomer**: A monomer is a small molecule that can join together with other similar molecules to form a polymer.
- **Polymer**: A polymer is a large molecule made up of repeating structural units (monomers).
- **Isomer**: Isomers are compounds that have the same molecular formula but different structural arrangements.
- **Epimer**: Epimers are a specific type of isomer that differ in configuration at only one specific carbon atom.

### Step 3: Classify CH₂=CH₂
Since ethene (CH₂=CH₂) can act as a building block for polymers, it is classified as a monomer. When many ethene molecules undergo a polymerization reaction, they can form a polymer known as polyethylene.

### Step 4: Conclusion
Thus, CH₂=CH₂ is a monomer that can polymerize to form polyethylene.

### Final Answer
CH₂=CH₂ is a **monomer**.

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