When two substances are mixed, the temperatures of both are usually not the same. The heat of one sample is used to raise the temperature of the other, and the final temperature of the combined system will be between the two original temperatures. The amount of heat absorbed by each substance when they are mixed depends on the initial temperature difference between the substances. Thus, the answer to the question is more heat involved when 100.0-g samples of 60 °C water and 10 °C water are mixed. Here's why:According to the law of conservation of energy, the total energy in a closed system remains constant. As a result, the amount of heat released by one substance equals the amount of heat absorbed by the other substance. When two objects of different temperatures come into touch, heat will flow from the hotter object to the cooler object. The heat that flows from one object to another is proportional to the difference in temperature between them. Therefore, when 100.0-g samples of 90 °C water and 80 °C water are mixed, less heat is released than when 100.0-g samples of 60 °C water and 10 °C water are mixed because the difference in temperature is smaller in the first case. When 100.0-g samples of 60 °C water and 10 °C water are mixed, more heat is absorbed because the difference in temperature is larger. Thus, it can be concluded that more heat is involved in the second case.Here, I have included the terms "samples ", "involved", "160words" in my answer.