Question

8 multiple choice 2 points
water cools from ( 2 ^ { circ } mathrm { c } ) to ( - 2 ^ { circ } mathrm { c } ). during this time, what happens to the motion of the molecules?
the motion of the molecules stops.
the motion of the molecules increases.
the motion of the molecules decreases.
the motion of the molecules remains the same.

Explanation:

Temperature is a measure of the average kinetic energy of molecules. As water cools from \(2^{\circ}C\) to \(- 2^{\circ}C\), its temperature decreases. Kinetic energy of molecules is directly related to temperature. When temperature decreases, the average kinetic energy of molecules decreases. Since kinetic energy is related to the motion of molecules (kinetic energy \(K = \frac{1}{2}mv^{2}\), where \(v\) is the speed of the molecule and is a measure of its motion), a decrease in kinetic energy means a decrease in the motion of the molecules.

Answer:

The motion of the molecules decreases.