Here's why:

* Kinetic Molecular Theory: This theory states that molecules in a substance are constantly in motion. The average kinetic energy of these molecules is directly proportional to the temperature of the substance.

* Distribution of Energies: The molecules in a liquid don't all have the same energy. Some will be moving faster than others. This distribution of energies is described by the Maxwell-Boltzmann distribution.

* Collisions: The molecules in a liquid constantly collide with each other, transferring energy. These collisions cause the speeds of individual molecules to change over time.

Key Points:

* Average Speed: While there's a wide range of speeds, the average speed of the molecules is related to the temperature of the liquid. Higher temperatures mean higher average speeds.

* Distribution: The shape of the Maxwell-Boltzmann distribution tells us that there's a range of speeds, with the most likely speed being near the average. Some molecules will be moving very slowly, while others will be moving very fast.

Analogy: Imagine a crowded room where people are moving around. Some people are walking slowly, others are running, and some might even be standing still. This is similar to the distribution of speeds of molecules in a liquid.