GEOLOGY
CRYSTALLOGRAPHY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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2
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4
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8
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Detailed explanation-1: -Contribution of corner particles: A particle at the corner of a unit cell is shared by eight-unit cells.
Detailed explanation-2: -An atom on an edge is shared by four unit cells, and an atom on a corner is shared by eight unit cells. Thus, only one-quarter of an atom on an edge and one-eighth of an atom on a corner can be assigned to each of the unit cells that share these atoms.
Detailed explanation-3: -A primitive cubic unit cell has atoms only at its corner. Each atom at a corner is shared between eight adjacent unit cells.
Detailed explanation-4: -A FCC unit cell contains four atoms: one-eighth of an atom at each of the eight corners (8×18=1 atom from the corners) and one-half of an atom on each of the six faces (6×12=3 atoms from the faces).
Detailed explanation-5: -You will notice that the atoms or ions at the edges of each face, or at the corners, are not complete spheres. In the simple cubic cell, each corner atom is shared by 8 different unit cells.