Which of the following represents surfactant molecule?

Options

A. `C_17H_36`
B. `C_17H25COO^-Na^+`
C. `H_2O`
D. None of these

Answer

To determine which of the given options represents a surfactant molecule, we need to understand the structure and characteristics of surfactants.

### Step-by-Step Solution:

1. **Definition of Surfactant**:
Surfactants, or surface-active agents, are compounds that lower the surface tension between two substances, such as a liquid and a solid, or between two liquids. They typically have a hydrophilic (water-attracting) head and a hydrophobic (water-repelling) tail.

2. **Identify Components of a Surfactant**:
A typical surfactant molecule consists of:
- A long hydrophobic tail (usually a hydrocarbon chain).
- A hydrophilic head (which can be ionic or polar).

3. **Analyze the Given Molecule**:
The molecule mentioned in the transcript is C17H25COO⁻Na⁺.
- The **C17H25** part represents the long hydrocarbon tail, which is hydrophobic.
- The **COO⁻** part represents the hydrophilic head, which is negatively charged and can interact with water.
- The **Na⁺** ion is a counterion that balances the charge of the COO⁻ head.

4. **Conclusion**:
Since this molecule has both a hydrophobic tail and a hydrophilic head, it qualifies as a surfactant. Therefore, the correct option representing a surfactant molecule is option B.

### Final Answer:
The correct option that represents a surfactant molecule is **option B (C17H25COO⁻Na⁺)**.