Final answer:
The true statements about particle motion and temperature are that the average kinetic energy of the particles in a substance determines its temperature and that faster moving particles generally result in a higher temperature of the substance.
Step-by-step explanation:
The relationship between particle motion and temperature is based on the kinetic-molecular theory. According to this theory, temperature is proportional to the average kinetic energy of the particles, such as molecules or atoms, in a substance. Therefore:
The average kinetic energy of the particles in a substance determines the substance's temperature.
If the particles in two pure substances have the same average speed, it does not necessarily mean they have the same temperature, since heavier particles will have more kinetic energy at the same speed, leading to different temperatures.
When two substances have the same temperature, it indicates that the average kinetic energy of the particles in both substances is the same, not that all of the particles are moving at the same speed, because particles have a range of speeds.
The speed of a substance's particles can give an indication of how hot or cold that substance is. Faster moving particles generally mean a higher temperature.
As such, the true statements are 1 and 4. Understanding that temperature is not simply a measure of particle speed, but rather the average kinetic energy involved, clarifies misconceptions about the nature of thermal energy and its measurement.