An element with molar mass $2.7 \times 10^{-2} \ kg \ mol^{-1}$ forms a cubic unit cell with edge length $405 \ pm$. If its density is $2.7 \times 10^{3} \ kg \ m^{-3},$ the radius of the element is approximately......... $\times 10^{-12} \ m$ (to the nearest integer).

Copper crystallises into a $fcc$ lattice with edge length $3.61 \times 10^{-8} \, cm$. Show that the calculated density is in agreement with its measured value of $8.92 \, g \, cm^{-3}$.

At $T \ K$,copper (atomic mass $= 63.5 \ u$) has $fcc$ unit cell structure with edge length of $x \ \mathring{A}$. What is the approximate density of $Cu$ in $g \ cm^{-3}$ at that temperature? $(N_A = 6.0 \times 10^{23} \ mol^{-1})$

Silver forms $ccp$ lattice and $X$-ray studies of its crystals show that the edge length of its unit cell is $408.6 \,pm$. Calculate the density of silver ( Atomic mass $= 107.9 \,u$ ).

$KF$ has a $NaCl$ type structure. What is the distance between $K^+$ and $F^-$ in $KF$ if the density is $2.48 \ g \ cm^{-3}$?

In an orthorhombic crystal system,the values of $a$,$b$,and $c$ are $4.2 \, \mathring{A}$,$8.6 \, \mathring{A}$,and $8.3 \, \mathring{A}$ respectively. Given the molar mass of the solute is $155 \, g \, mol^{-1}$ and the density is $3.3 \, g \, cm^{-3}$,calculate the number of formula units $(Z)$ per unit cell.