Q1: Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface ?

ANS:D - Interfacial tension

The most controlling factor for the rate of bubble detachment from a hot solid surface is the interfacial tension. Interfacial tension refers to the force acting along the interface between two immiscible phases, such as a liquid and a gas (e.g., bubbles). When bubbles form on a hot solid surface, the interfacial tension plays a crucial role in determining how strongly the liquid adheres to the surface and whether the bubble can detach. A lower interfacial tension allows bubbles to detach more easily from the surface, while a higher interfacial tension tends to keep bubbles adhered to the surface. Liquid density, liquid viscosity, and hot surface temperature can also influence bubble detachment, but to a lesser extent compared to interfacial tension. For example:

• Liquid density: Higher liquid density may increase the buoyancy force acting on the bubble, which could affect its detachment, but this effect is usually secondary to interfacial tension.
• Liquid viscosity: Higher viscosity may hinder bubble movement, but it may not significantly affect the detachment process itself.
• Hot surface temperature: While surface temperature affects bubble formation and growth, it primarily influences the rate of bubble nucleation rather than detachment.