Answer:
1. The 1500 kg of water will reach a higher temperature.
2. An isolated system is one in which matter and energy are not exchanged with the surroundings.
Step-by-step explanation:
In the first case, the mass is inversely proportional to the temperature at constant rate of energy absorbtion. When the mass is decreased, then an increase in temperature. So, 1500 kg of water would have a higher temperature compared to that of 2500 kg.
In the second case, when a system is an isolated one, it implies that it share nothing with her surroundings. An example is a hot water in a well lagged thermosflask, which do not share its mass and temperature with her surroundings.