In $CsCl$ type structure, if the radius of the cation and anion are $80 \ pm$ and $100 \ pm$ respectively, then the closest distance between two cations is:

Ferrous oxide has a cubic structure and each edge of the unit cell is $5.0 \, \mathring{A}$. Assuming the density of the oxide is $4.0 \, g \, cm^{-3}$,the number of $Fe^{2+}$ and $O^{2-}$ ions present in each unit cell will be ($M_w$ of $FeO = 72$)

An element crystallizes in an $fcc$ structure with an edge length of $200 \, pm$. If $200 \, g$ of this element contains $24 \times 10^{23}$ atoms,calculate its density in $g \, cm^{-3}$.

Calculate the density of an element having molar mass $225 \text{ g mol}^{-1}$ forming a $bcc$ structure. Given: $[a^3 \times N_A = 75 \text{ cm}^3 \text{ mol}^{-1}]$ (in $\text{ g cm}^{-3}$)

An element $X$ (At. wt. $= 80 \ g/mol$) has an $fcc$ structure. Calculate the number of unit cells in $8 \ g$ of $X$.

Ammonium chloride crystallizes in a body-centered cubic lattice with an edge length of the unit cell of $390 \ pm$. If the size of the chloride ion is $180 \ pm$,the size of the ammonium ion would be ........... $pm$.