Which of the following is not true about

Which of the following is not true about the ionic solids?

(i) Bigger ions form the close-packed structure.

(ii) Smaller ions occupy either the tetrahedral or the octahedral voids

depending upon their size.

(iii) Occupation of all the voids is not necessary.

(iv) The fraction of octahedral or tetrahedral voids occupied depends upon

the radii of the ions occupying the voids.