Final answer:
Fuel particles become smaller as the ratio of surface-to-mass increases.
Step-by-step explanation:
Fuel particles become smaller as the ratio of surface-to-mass increases. This is because as the surface area of a particle increases, the mass stays the same. For example, let's consider a cube with a side length of 1 cm. The surface area of this cube is 6 cm², while the volume (and hence the mass) is 1 cm³. Now, if we decrease the side length to 0.1 cm, the surface area becomes 0.6 cm², which is smaller than before.