Question

For any liquid, the number of drops formed per unit volume depends on (a) viscosity (b) surface tension (c) pressure (d) none

Short answer

The factors that affect the formation of drops in any liquid per unit volume are viscosity and surface tension.

Step-by-step solution

Analyzing Effect of Viscosity

Viscosity refers to a fluid's resistance to shear or flow deformation. A liquid with high viscosity will experience a stronger internal friction. This would make it more difficult for the liquid to divide into separate drops. So, the viscosity does affect the number of drops formed.

Analyzing Effect of Surface Tension

Surface tension can be thought of as the tendency of the surface of a liquid to contract into the smallest possible surface area. The greater the surface tension of a liquid, the more it is resistant to the creation of new surface area, i.e., making new drops. Thus, surface tension influences the number of drops formed.

Analyzing Effect of Pressure

Pressure does impact the properties of a liquid but does not directly influence the number of drops formed per unit volume. So, this option is incorrect.

Conclusion

After examining each factor, it is clear that viscosity and surface tension influence the number of drops formed per unit volume in any liquid, while pressure does not have a direct impact.

Key concepts

Viscosity

Viscosity is like the thickness of a liquid. It describes how easily a liquid flows. Imagine trying to pour honey compared to water. Honey is thicker; therefore, it has a higher viscosity.
Viscosity impacts how liquid forms into drops. Here’s how: - **High Viscosity**: Means more internal friction. Difficult for the liquid to break into drops. Think of such fluids as sticky. - **Low Viscosity**: Easier flow and formation of droplets. These fluids are more fluid-like and pour easily. - Viscosity is a property controlled by temperature. For instance, warming up honey makes it flow more like water, decreasing its viscosity. Understanding viscosity helps us see why some liquids create fewer droplets than others.

Pressure

Pressure is the force exerted by the liquid’s molecules against its container or environment. It’s an important property in fluid dynamics but doesn’t directly shape how droplets form. Here’s why pressure doesn’t play a big role in droplet formation: - **Fluid Dynamics**: While pressure influences the speed and behavior of liquids, it doesn’t alter how a liquid divides into droplets. - **Atmospheric Pressure**: Changes might affect the liquid as a whole, not individual droplets. The crucial takeaway is that while pressure affects many properties of a fluid, it is not a deciding factor in droplet number per unit volume.

Liquid Droplet Formation

The formation of liquid droplets involves the creation of small, discrete units of a liquid from a larger mass. This process depends mainly on: - **Surface Tension**: Surface tension seeks to minimize surface area. For droplet formation, a liquid with high surface tension resists breaking into droplets. - **External Forces**: Applied forces, like pouring or shaking, can influence how easily the liquid breaks apart. When liquid forms droplets, the balance between surface tension and viscosity is crucial. High viscosity and high surface tension usually result in fewer droplets because the fluid resists division. - **Best Example**: Water on a waxy surface. It beads up due to surface tension trying to minimize the contact area. In essence, liquid droplet formation is an outcome of these forces working together, ultimately affecting how a liquid behaves and interacts in its environment.