During cooling, the kinetic energy of the molecules falls. why does this happen?

The correct answer of this question is : Molecular motion or vibration slows down

EXPLANATION :

The kinetic energy of the molecule depends on the molecular motion. Molecules might have different types of kinetic energy depending on the type of substance i.e solid,liquid or gases.

During cooling, we are reducing the temperature of the substance. Due to the decrease of temperature, the molecular speed is also decreased. It is so because the molecular speed is dependent on the temperature of the substance.

Hence, the vibration, rotation or translation motion of the molecule slows down during cooling, which in turn, decreases the kinetic energy of the molecule.

3. dark matter

empty space could also be a simple vacuum