Packing in Solids

In $\mathrm{hcp}$ lattice, if a plane is drawn parallel to layers $\mathrm{A}$ and $\mathrm{B}$, at a distance $\frac{\mathrm{c}}{8}$ above the layer $\mathrm{B}$, it passes through centres of $\mathrm{x}$ tetrahedral and $\mathrm{y}$ octahedral voids. A plane parallel to layer $\mathrm{A}$, at a distance $\frac{\mathrm{c}}{8}$ just below it passes through centres of $\mathrm{p}$ tetrahedral and $\mathrm{q}$ octahedral voids. Find $\left(\mathrm{x}+\mathrm{y}+\mathrm{p}+\mathrm{q}\right)$. $\mathrm{c}$ is the cell parameter of hcp lattice, the vertical edge length.

The correct statement(s) for hexagonal closed packed metallic crystal is:

A two dimensional solid is made by alternating circles with radius $\mathrm{a}$ and $\mathrm{b}$ such that the sides of the circles touch. The packing fraction is defined as the ratio of the area under the circles to the area under the rectangle with sides of length $\mathrm{x}$ and $\mathrm{y}.$

The ratio $\mathrm{r}=\mathrm{b}/\mathrm{a}$ for which the packing fraction is minimized is closest to:

Atoms of an element $\mathrm{Z}$ form hexagonal closed packed $\left(\mathrm{hcp}\right)$ lattice and atoms of element $\mathrm{X}$ occupy all the tetrahedral voids. The formula of the compound is

In reference to crystal structure, explain the meaning of the coordination number.

The space occupied by $\mathrm{BCC}$ arrangement is approximately

The number of hexagonal faces that are present in a truncated octahedron is

Co-ordination number of atoms in $\mathrm{HCP}$is:

In a crystalline solid $\mathrm{x}$ atoms occupy hcp and $\frac{1}{4}$th of tetrahedral voids are occupied by $\mathrm{y}$ atoms. Then empirical formula of crystalline solid is:

In one dimensional close packed arrangement, the coordination number is _____ .

In one dimensional close packed arrangement, the coordination number is $2$.

Give the coordination number in close packing of lattice points in one dimension ?

How will you distinguish between the following pairs of terms:

Hexagonal close-packing and cubic close packing.

How will you distinguish between the following pairs of terms? 

Hexagonal close packing and cubic close packing.

An element crystallises in BCC structure. The edge length of its unit cell is $288 \mathrm{pm}.$ If the density of the crystal is $7.2 {\mathrm{gcm}}^{-3},$ what is the atomic mass of the element?

How many number of edges are present in an $\mathrm{HCP}$ unit cell?

What is the two dimensional coordination number of a molecule in square close packed layer? 

Explain with the help of neat diagrams AAAA and ABAB and ABCABC type of three dimensional packings.

The number of atoms present in a hexagonal close packed unit cell is: