$Na$ and $Mg$ crystallise in $b.c.c.$ and $f.c.c.$ type crystals respectively. The number of atoms of $Na$ and $Mg$ present in the unit cell of their respective crystals is:

If the length of the body diagonal of a $FCC$ unit cell is $x \ \mathring{A}$, the distance between two nearest octahedral voids in the cell in $\mathring{A}$ is

The $FCC$ crystal contains how many atoms in each unit cell?

An ionic solid $AB$ crystallizes in a $NaCl$-type structure,where $A$ ions are at the corners of the cube. If all face-centered ions along one axis are removed,then the stoichiometry of the resulting solid will be .....

$A$ cubic solid is made up of two elements $X$ and $Y$. Atoms of $X$ are present on every alternate corner and one at the center of the cube. $Y$ is at $\frac{1}{3}$ of the total faces. The empirical formula of the compound is

Coordination number of $Zn^{2+}$ in $ZnS$ (zinc blende) is