CsCl has eightfold coordination but its two-ion arrangement is not a close-packed structure. In fluorite CaF₂ the calcium sublattice is FCC, with fluoride in all tetrahedral holes and calcium coordination eight. Thus the assertion that both are close packed is false, D. The source’s “bcc type” describes the CsCl motif; its Bravais lattice with distinct ions is primitive cubic.
More Solids: Crystal systems and lattices, Miller planes, crystal packing, crystal defects, Bragg’s law, ionic crystals, structure of AX, AX2, ABX3 type compounds, spinels, band theory, metals and semiconductors, Zeolites and their applications. questions