The kinetic energy of water molecules is directly related to the temperature of the water. The higher the temperature, the greater the kinetic energy of the molecules.
From the temperatures given:
- Sample 1: 98.2 °C
- Sample 2: 46.0 °C
- Sample 3: 100.6 °C
- Sample 4: 31.4 °C
Sample 4 has the lowest temperature at 31.4 °C, which means it has the lowest kinetic energy among the samples.
Therefore, the sample with the lowest kinetic energy is Sample 4.