Water in benzene is emulsified by  

Options

A. soap
B. mercuric iodide
C. egg albumin
D. grease

Answer

To solve the question "Water in benzene is emulsified by," we need to identify the correct emulsifier from the given options: soft mercury chloride, agar, albumin, and grease.

### Step-by-Step Solution:

1. **Understanding Emulsions**:
- An emulsion is a mixture of two immiscible liquids, where one liquid is dispersed in the other. In this case, we have water (a polar liquid) and benzene (a non-polar liquid).

2. **Role of Emulsifiers**:
- Emulsifiers are substances that help stabilize emulsions by reducing the surface tension between the two immiscible liquids, allowing them to mix more easily.

3. **Analyzing the Options**:
- **Soft Mercury Chloride**: This is a chemical compound that can act as an emulsifier.
- **Agar**: A gelatinous substance derived from algae, often used as a thickening agent, but not typically an emulsifier for liquid-liquid systems.
- **Albumin**: A protein that can stabilize emulsions, but it is more commonly used in food emulsions rather than in organic solvents like benzene.
- **Grease**: Generally a thick, oily substance that does not act as an emulsifier for water in organic solvents.

4. **Selecting the Correct Emulsifier**:
- Among the options, soft mercury chloride is known to be effective in stabilizing emulsions of water in organic solvents like benzene.

5. **Conclusion**:
- Therefore, the correct answer is **soft mercury chloride**.

### Final Answer:
Water in benzene is emulsified by **soft mercury chloride**.