The motion of molecules would decrease at a molecular level if a liquid is placed in cool conditions.
C. The motion of the molecules would decrease.
Step-by-step explanation:
For the change in the state of matter in a substance, particle movements are responsible. Thus, an increase in motion means high kinetic energy and vice versa. Also, kinetic energy and temperature are directly proportional to each other.
When a liquid is placed in colder conditions, the particles in it come closer because the motion among molecules decreases at a molecular level. This leads to low kinetic energy among molecules because the temperature is a measure of kinetic energy.