The average kinetic energy of the particles is greatest in Beaker D: 18°C.
The average kinetic energy of particles in a substance is directly proportional to its temperature. Kinetic energy is a measure of the motion of particles. In this case, we have four beakers with different temperatures: 3°C, 9°C, 15°C, and 18°C.
According to the kinetic theory of gases, an increase in temperature corresponds to an increase in the average kinetic energy of the particles in a substance. Therefore, the beaker with the highest temperature, Beaker D at 18°C, would have the greatest average kinetic energy of the particles.
At higher temperatures, the particles in the saltwater will have greater motion and higher velocities. This increased kinetic energy results in more collisions between particles and a higher overall energy state. Hence, the beaker with the highest temperature, Beaker D: 18°C, would have the greatest average kinetic energy of the particles. Therefore, Option D is correct.
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