Final answer:
The best emulsifying agent is sodium stearate (CH₃(CH₂)₁₀COONa), which is commonly used in soaps. It has a hydrophobic tail and a hydrophilic head, allowing it to stabilize emulsions between hydrophobic and hydrophilic substances.
Step-by-step explanation:
The best emulsifying agent is A) CH₃(CH₂)₁₀COONa, also known as sodium stearate. Emulsifying agents are compounds that help stabilize an emulsion, which is a colloid formed by the dispersion of a hydrophobic liquid in water or a hydrophilic liquid in oil. Sodium stearate, a long-chain carboxylic acid salt, is commonly used as an emulsifying agent in soaps due to its amphiphilic nature. It has a hydrophobic tail and a hydrophilic head, enabling it to form a stable emulsion between hydrophobic and hydrophilic substances.