Final answer:
In welding, quenching refers to rapidly cooling a metal to alter its microstructure and mechanical properties. Water would more effectively reduce the metal's temperature compared to ice because it has a greater specific heat capacity.
Step-by-step explanation:
The term "quenching" in welding refers to b. Rapidly cooling a metal. This process is critical in controlling the microstructure and mechanical properties of the metal. By quickly lowering the temperature of a hot piece of metal, usually done by immersing it in a quenching medium like water, oil, or air, the metal undergoes a transformation that affects its hardness and strength.
Regarding the comparison between cooling with water and ice, water would be more effective in reducing the temperature of a hot metal. This is due to water having a greater specific heat capacity than ice, meaning it can absorb more heat energy without its temperature rising as much, thereby extracting heat from the metal more efficiently.