Water does not wet an oily glass because

Options

A. cohesive force of oil ` gt` adhesive force between oil and glass
B. cohesive force of oil ` gt` cohesive force of water
C. oil repels water
D. cohesive force of water ` gt` adesive force between water and oil molecules

Explanation

To solve the question "Water does not wet an oily glass because," we need to analyze the interaction between water, oil, and the glass surface. Here’s a step-by-step explanation:

### Step 1: Understand Cohesive and Adhesive Forces
- **Cohesive Forces**: These are the forces that hold the molecules of the same substance together. In the case of water, cohesive forces are responsible for water molecules sticking to each other.
- **Adhesive Forces**: These are the forces that attract molecules of different substances to each other. For water, this would involve the attraction between water molecules and the molecules of the oily surface.

### Step 2: Compare the Forces
- In the case of water and an oily surface, the cohesive forces among water molecules are stronger than the adhesive forces between water and the oil molecules on the glass.
- This means that water molecules prefer to stick to each other rather than spreading out to wet the oily surface.

### Step 3: Conclusion
- Since the cohesive forces of water are greater than the adhesive forces between water and oil, water does not spread out or wet the oily glass surface. Instead, it forms droplets.

### Final Answer
Thus, the correct answer to the question is: **Water does not wet an oily glass because the cohesive force of water is greater than the adhesive force between the water and oil molecules.**