Final answer:
If a block of ice is placed on a stainless steel block at 500°C, the ice would melt and eventually evaporate, with the average kinetic energy of the molecules increasing until each phase change is complete.
Step-by-step explanation:
If a block of ice is placed on top of a stainless steel block at a temperature of 500 degrees Celsius, the ice would undergo several phase changes. Initially, the average kinetic energy of the molecules in the ice would increase as the ice gains energy from the hot stainless steel. This energy transfer would cause the ice molecules to vibrate more rapidly, leading to the melting of the ice as the temperature at the ice-stainless steel interface reaches 0°C. During the melting process, the temperature of the ice-water mixture remains constant. Once the ice has completely melted into water, the average kinetic energy of the water molecules continues to increase until the water reaches its boiling point and begins to evaporate.
Based on the given options, the correct answer would be (a) The ice would melt, and the average kinetic energy of the molecules would increase. This is because the heat from the stainless steel would first cause the ice to melt, and then, as heating continues, the liquid water would eventually evaporate. The temperature and hence the kinetic energy of the molecules increase until a phase change occurs, at which point the temperature remains constant until the phase change is complete.