Question

Match the crystalline solids in Column-I with the coordination number of their ions in Column-II.

Answer 1

(A) In this arrangement, the $C{l}^{-}$ions are present at the corners of the unit cell and the $C{s}^{+}$ ions at the centre of the cube. Each $C{s}^{+}$ ion is surrounded by eight $C{l}^{-}$ ions and each $C{l}^{-}$ ion is surrounded by eight $C{s}^{+}$ ions. Thus, the structure has a $8:8$ coordination.

(B) In $Ca{F}_2$, the coordination number of cation and anion are $8$ and $4$. Each $C{a}^{+2}$ ion is surrounded by eight $F^{-}$ ions, giving a body centered cubic type of arrangement and each $F^{-}$ ion is tetrahedrally surrounded by four $C{a}^{+2}$ ions. The calcium Flouride structure is also known as the Flourite structure.

(C) In zinc blende structure $\left(ZnS\right)$, sulphide ions are face-centred and zinc is present in alternate tetrahedral voids. Coordination number of Zinc is $4$ and that of sulphide is $4$.

(D) $N{a}_{2}O$ has an antiflurite structure. In this structure the anions are arranged in cubic close packing (ccp), while the cations occupy all the tetrahedral voids. So the coordination number of anion is $8$ and cation is $4$.