If the atoms are treated as solid spheres,the fraction of volume occupied by the atoms in a face-centered-cubic unit cell is A)0.45 B)0.52 C)0.65 D)0.68 E)0.74

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Quizplus · Accepted Answer

In a face-centered cubic (FCC) unit cell, atoms are located at each of the corners and the centers of all the faces. Each corner atom is shared among eight unit cells and each face-centered atom is shared between two, so the effective number of atoms per unit cell is 4. The packing efficiency, or the fraction of volume occupied by the atoms, in an FCC structure is 0.74, assuming the atoms are hard spheres.

If the Atoms Are Treated as Solid Spheres,the Fraction of Volume