Kinetic energy of particles in a substance is directly related to its temperature. The lower the temperature, the lower the kinetic energy.
Looking at the temperatures recorded:
- 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.
Therefore, the sample with the lowest kinetic energy is 4.