Close Packed Structures and Packing Efficiency

The coordination number of a metal crystallizing in a hexagonal close-packed structure is:

$\mathrm{CsBr}$ has bcc structure with edge length $4.3 \mathrm{\AA }$ . The shortest inter ionic distance in between ${\mathrm{Cs}}^{+}$ and ${\mathrm{Br}}^{-}$ is:

The edge length of a face-centred cubic cell of an ionic substance is $508 \mathrm{pm}$. If the radius of the cation is $110 \mathrm{pm}$, the radius of anion is 

What is the coordination number of sodium in sodium oxide $\left({\mathrm{Na}}_2\mathrm{O}\right)$?

The number of octahedral sites per sphere in FCC structure is 

In a compound, atoms of elements $\mathrm{Y}$ form ccp lattice and those of element $\mathrm{X}$ occpy $\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.\mathrm{rd}$ of tetrahedral voids. The formula of the compound will be 

Percentage of free space in cubic close-packed structured and in a body centred packed structure are respectively

Interstitial sites that are formed when three closed packed spheres of one layer is put on three close packed spheres of the second layer, their positions being inverted with respect to each other.

A tetrahedral void in $\mathrm{fcc}$ is formed by atoms at

Number of formula units in unit cell of $\mathrm{MgO}$ (rock salt), $\mathrm{ZnS}$ (zinc blende) and $\mathrm{Pt}$ (fcc) respectively

What is the coordination number of ${\mathrm{Rb}}^{+}$ in $\mathrm{RbBr}$ unit cell if ionic radii of ${\mathrm{Rb}}^{+}$ and ${\mathrm{Br}}^{-}$ions being $148$ and $195$ respectively?

In normal spinel structure there is a closed packed array of ${\mathrm{O}}^{2-}$ions. The trivalent cations are present in

$\mathrm{KF}$ has $\mathrm{NaCl}$ type of structure. The edge length of its unit cell has been found to be $537.6 \mathrm{pm}$. The distance between ${\mathrm{K}}^{+}{\mathrm{F}}^{-}$ in $\mathrm{KF}$ is

For tetrahedral co-ordination, the radius ratio $\left({\mathrm{r}}_{+}/{\mathrm{r}}_{-}\right)$ should be

The packing efficiency of the $2\mathrm{D}$ square cell shown below is

In a BCC unit cell, if half of the atoms per unit cell are removed, then percentage void is

In a ccp type structure, if half of the face-centred atoms are removed, then percentage void in unit cell is approximately

The coordination number in one dimensional close packed arrangement is