In the face-centered unit cell,the lattice points are present at

An ionic solid is $HCP$ of $B^{2-}$ ions and $A^{x+}$ ions are in one-fourth of tetrahedral voids. The value of $x$ should be

In a crystalline solid with the formula $AB_2O_4$,the oxide ions are arranged in a cubic close-packed $(CCP)$ lattice,while the cations $A$ are present in tetrahedral voids and cations $B$ are present in octahedral voids. What are the percentages of tetrahedral and octahedral voids occupied by $A$ and $B$ respectively?

$A$ compound formed by $Mg$,$Al$,and $O$ is found to have a cubic close-packed $(CCP)$ array of oxide ions,in which $Mg^{2+}$ ions occupy $\frac{1}{8}^{th}$ of the tetrahedral voids and $Al^{3+}$ ions occupy $\frac{1}{2}$ of the octahedral voids. The formula for the compound is:

$A$ compound is formed by $X$ and $Y$ elements. Atoms of $Y$ (anions) form $hcp$ lattice. Atoms of $X$ (cations) are in some octahedral holes. The formula of the compound is $XY_3$. What is the fraction of octahedral holes unoccupied by $X$?

The contribution of a particle at the edge center to a particular unit cell is: