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Q.
In $FCC$ lattice $A , B , C , D$ atoms are arranged at corners, face centres, octahedral voids and tetrahedral voids respectively, then the body diagonal contains.
The Solid State
Solution:
Body diagonal contain two atoms at comers, one octahedral void and two tetrahedral voids.
$A$ & $3B$ ($3B$ present at top, back and left face) forms tetrahedral void in which $D$ is present.
