In which of the following structures coordination number for cations and anions in the packed structure will be same

a. Cl ^–  ions form fcc lattice and Na⁺   ions occupy all octahedral voids of the unit cell

b. Ca ²⁺ ions form fcc lattice and F ^–  ions occupy all the eight tetrahedral voids of the unit cell

c. O ^2-   ions form fcc lattice and Na⁺   ions occupy all the eight tetrahedral voids of the unit cell

d. S ^2- ions form fcc lattice and Zn²⁺   ions  go into alternate tetrahedral voids of the unit cell

Ans.a

Explanation : NaCl crystal have rock salt structure having fcc lattice in which Cl^{– ions are present at fcc lattice points and face centre and Na +    occupies all  the octahedral void of given unit cell} 

Where, coordination number of Na ^{+  = 6} 

Coordination number or Cl ^–  =  6

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