ANS:A - Sphere

Among the given options, a sphere has the maximum value of sphericity. Here's why:

1. Definition of Sphericity:
   • Sphericity is a measure of how closely a particle's shape approximates that of a sphere.
   • It is defined as the ratio of the surface area of a sphere having the same volume as the particle to the surface area of the particle itself.
2. Shapes and Sphericity:
   • Sphere: A sphere has the highest possible sphericity value of 1. This is because a sphere has the smallest surface area for a given volume compared to any other shape.
   • Cube: A cube has a lower sphericity compared to a sphere because it has a larger surface area relative to its volume.
   • Cylinder (L/D = 1): A cylinder with a length-to-diameter ratio of 1 (meaning it is as tall as it is wide) has a lower sphericity than a sphere because its surface area is larger for the same volume.
   • Raschig Rings: Raschig rings are cylindrical rings used in chemical processing and have even lower sphericity than a cylinder because they have more surface area relative to their volume due to their open structure.
3. Conclusion:
   • Since sphericity is defined based on how closely a particle resembles a sphere, a sphere itself, by definition, has the maximum sphericity value of 1.
   • Among the options provided (sphere, cube, cylinder with L/D = 1, Raschig rings), the sphere has the highest sphericity value.