$A$ metal $(M)$ crystallizes in an $fcc$ lattice with an edge length of $4.242 \mathring{A}$. What is the radius of the $M$ atom (in $\mathring{A}$)?

$A$ metal has a $bcc$ structure. If the distance between two nearest atoms is $1.73 \ \mathring{A}$, what is the edge length of the unit cell in $pm$?

Calculate the edge length of the unit cell of a metal which crystallises in a $bcc$ structure. (Radius of metal atom $= 173 \ pm$)

The density of $Na$ is $0.613 \ g \ cm^{-3}$. If the edge length of the unit cell of $Na$ is $5 \ \mathring{A}$,the effective number of atoms of $Na$ per unit cell is (Atomic weight of $Na = 23 \ u$)

Gold crystallises in $fcc$ lattice. The edge length of the unit cell is $4 \ \mathring{A}$. The closest distance between gold atoms is '$x$' $\mathring{A}$ and density of gold is '$y$' $g \ cm^{-3}$. What are $x$ and $y$ respectively?
$($ Molar mass of gold $= 197 \ g \ mol^{-1} ; N_A = 6 \times 10^{23} \ mol^{-1} )$

The inter-planar spacing between the $(2, 2, 1)$ planes of a cubic lattice of length $450 \, pm$ is $.... \, pm$