Biodegradable detergents contains:

Options

A. n-alkyl chain
B. polyester group
C. phenyl side chain
D. cyclohexyl side chain

Answer

To determine what biodegradable detergents contain, we need to analyze the options provided and understand the structural implications of each.

### Step-by-Step Solution:

1. **Understanding Biodegradable Detergents**:
- Biodegradable detergents are substances that can be broken down by microorganisms into non-toxic substances. This means that their chemical structure should not be too complex, allowing for easier decomposition.

2. **Analyzing the Options**:
- **Option 1: N-alkyl chain**:
- An N-alkyl chain consists of a straight or branched alkyl group attached to a nitrogen atom. This structure is relatively simple and can be easily broken down by microorganisms.
- **Option 2: Polyester group**:
- A polyester group contains multiple ester linkages (–COO–) and tends to have a more complex structure. This complexity can hinder biodegradation as it may not be easily broken down by microorganisms.
- **Option 3: Phenyl side chain**:
- A phenyl side chain involves a benzene ring, which is a stable and complex structure. The presence of such rings can make the compound resistant to biodegradation.
- **Option 4: Cyclohexyl side chain**:
- A cyclohexyl side chain is also a cyclic structure. Similar to the phenyl side chain, it adds complexity and can make biodegradation more difficult.

3. **Conclusion**:
- Among the options, the N-alkyl chain is the simplest structure that can be easily broken down by microorganisms, making it suitable for biodegradable detergents. The other options (polyester group, phenyl side chain, and cyclohexyl side chain) are more complex and would not degrade as easily.

### Final Answer:
**Biodegradable detergents contain: N-alkyl chain.**

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