which of the following statement is correct for the `NaCl` lattice?

Options

A. An `Na^(+)` ion is placed at a distance of `(1)/(sqrt(2))a` directly above each `Cl^(-)` (where a is the cube unit cell edge length).
B. An `Na^(+)` ion is placed at a distance of `(1)/(2sqrt(2))` a directly above each `Cl^(-)` ion.
C. An `Na^(+)` ions is placed at a distance of `(1)/(6)a` directly above each `Cl^(-)` ion
D. An `Na^(+)` ion is placed at a distance of `(1)/(2)a` directly above each `Cl^(-)`.

Answer

4

Explanation

Simple ionic solids such a `NaCl` are like metals in that the individual ions are spheres that pack together in a regular way.However they differ from metals in that the spheres are not all the same size-anions are generally larger than cations . As a result ,ionic soilds adopt a variety fo different unit cells depending on the size and charge of the ions.`NaCl` has a face -centered cubic unit cell in which is the larger `CI^(-)` anions occupy corners and face centres , while the smaller `Na^(+)` cations fit into the octahedral holes between adjacent `CI^(-)` ions.