How many atoms are contained in a unit cell for a simple cubic unit, a body-centered cubic unit, and a face-centered cubic unit?

Briefly compare the packing efficiency of the unit cells for a simple cubic unit, a body-centered cubic unit, and a face-centered cubic unit?

Consider the unit cell of a face-centred cubic structure of platinum (Pt) atoms, each with radius 139 pm.  The unit cell and arrangement of atoms centred on a plane within the unit cell are shown below.

In an experiment, you measure the proportion of unit cells that occupied by atoms. For one cell, you measure 52% of the cell i occupied by atoms (with 48% empty space), for another cell, y measure 68% is occupied by atoms (with 32% empty space) ar for a 3rd cell you measure 74% is occupied by atoms and 26% i empty space. Which one of these should be the face-centered cubic arrangement? is ½ of a sphere. There are 6 faces, so this gives a total each 2 edge 52% occupied by atoms 74% occupied by atoms & C. Cell type 68% occupied by atoms none are true Num