What is the atomic radius of an element if it crystallises in a $BCC$ structure with an edge length of unit cell $287 \ pm$ (in $pm$)?

What is the relationship between the edge length $(a)$ and the radius of the atom $(r)$ in a simple cubic unit cell?

Calculate the volume of the unit cell for an element having a molar mass of $92 \ g \ mol^{-1}$ that forms a $bcc$ structure,given $\left[\varrho \times N_{A} = 5.0 \times 10^{24} \ g \ cm^{-3} \ mol^{-1}\right]$.

If the radii of $Na^{+}$ and $Cl^{-}$ are $95 \, pm$ and $181 \, pm$ respectively, then the edge length of the $NaCl$ unit cell is equal to ...... $pm$.

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 $= 107.9 \,u$ ).

For a $Cr$ crystal crystallizing in a $bcc$ structure, the edge length of the unit cell is $287 \, pm$. What is the density of the crystal in $\text{g/cm}^3$? $(Cr = 51.99 \, \text{g/mol})$