Final answer:
Smaller particles have the largest surface area per unit weight compared to larger particles.
Step-by-step explanation:
In terms of the surface area per unit of weight, smaller particles have a larger surface area per unit weight compared to larger particles. This is because as the size of a particle decreases, the surface area-to-volume ratio increases.
For example, let's compare a sphere with a diameter of 1 cm and a sphere with a diameter of 2 cm. The surface area of the sphere with a diameter of 1 cm is 3.14 cm², while the surface area of the sphere with a diameter of 2 cm is 12.57 cm². The smaller sphere has a larger surface area per unit weight compared to the larger sphere.
Therefore, smaller particles have the largest surface area per unit weight.