Surface tension of a liquid is a molecular phenomenon of liquids involving the force of cohesion along the liquid molecules. It is scalar quantity and is numerically equal to the surface energy. Numerically, it is proved that the potential soluble salts and surface active substance. Sparingly soluble salts and surface active substances decrease the surface tension of the liquid. However, the fairly soluble solutes increase the surface tension of the liquid. Surface tension of a liquid is independent of surface area but it depends on the intermolecular forces and the temperature.
When oil is placed on the surface of hot water, formation of droplets takes place because :

Options

A. surface tension not hot water = surface tension of oil
B. surface tension not hot water `lt` surface tension of oil
C. surface tension not hot water `gt` surface tension of oil
D. none of the above.

Explanation

To solve the question regarding the formation of droplets when oil is placed on the surface of hot water, we need to analyze the concepts of surface tension and the interactions between different liquids.

### Step-by-Step Solution:

1. **Understanding Surface Tension**:
- Surface tension is a property of liquids that arises due to cohesive forces between liquid molecules. It is a measure of the elastic tendency of a fluid surface and is defined as the force per unit length acting at the surface of a liquid.

2. **Cohesion vs. Adhesion**:
- Cohesion refers to the attraction between molecules of the same substance (e.g., water molecules attracting each other), while adhesion refers to the attraction between molecules of different substances (e.g., water molecules attracting oil molecules).

3. **Different Surface Tensions**:
- When oil is placed on hot water, the surface tension of hot water is different from that of oil. The intermolecular forces in water (hydrogen bonding) are significantly stronger than those in oil (van der Waals forces).

4. **Formation of Droplets**:
- Due to the difference in surface tension, when oil is added to water, the oil does not spread out evenly. Instead, it forms droplets. This occurs because the cohesive forces within the water molecules are stronger than the adhesive forces between the water and oil molecules.

5. **Boundary Formation**:
- The difference in surface tension creates a boundary between the two liquids. This boundary is characterized by the formation of droplets of oil on the surface of the water.

6. **Conclusion**:
- The formation of droplets occurs because the surface tension of hot water is not equal to the surface tension of oil, leading to the creation of a distinct interface between the two liquids.

### Final Answer:
When oil is placed on the surface of hot water, the formation of droplets takes place because the surface tension of hot water is not equal to the surface tension of oil.