An element crystallises in $bcc$ type crystal structure with an edge length of unit cell $300 \ pm$. Calculate the radius of the element.

Tobacco seed globin forms face-centered cubic crystals with a unit cell dimension of $12.3 \, nm$ and a density of $1.287 \, g \, cm^{-3}$. Its molecular mass will be:

Lithium crystallises into a body-centered cubic $(BCC)$ structure. What is the radius of lithium if the edge length of its unit cell is $351 \ pm$ (in $pm$)?

Element $X$ crystallizes in a $12$ coordination face-centered cubic $(fcc)$ lattice. On applying high temperature,it changes to an $8$ coordination body-centered cubic $(bcc)$ lattice. Find the ratio of the density of the crystal lattice before and after applying high temperature. The atomic radius of $X$ is the same in both crystals.

Ionic radii of cation $A^{+}$ and anion $B^{-}$ are $102 \ pm$ and $181 \ pm$ respectively. These ions are allowed to crystallize into an ionic solid. This crystal has cubic close packing for $B^{-}$ and $A^{+}$ is present in all octahedral voids. The edge length of the unit cell of the crystal $AB$ is $pm$.

Calculate the molar mass of an element with density $2.7 \ g \ cm^{-3}$ that forms $fcc$ structure. $\left[a^3 \cdot N_{A}=40 \ cm^3 \ mol^{-1}\right]$