Calculate the coordination number of $Na^{+}$ in $NaCl$ crystal, given the radii of $Na^{+}$ and $Cl^{-}$ are $95 \ pm$ and $181 \ pm$ respectively.

An $fcc$ unit cell of aluminium contains the equivalent of how many atoms?

For an ionic crystal of the general formula $AX$ and coordination number $6$,the value of radius ratio will be

The coordination number of a metal crystallizing in a hexagonal close packed structure is

$Na$ and $Mg$ crystallize in $BCC$ and $FCC$ type crystals respectively,then the number of atoms of $Na$ and $Mg$ present in the unit cell of their respective crystal is

An ionic compound is expected to have a tetrahedral structure if the radius ratio $r_{+} / r_{-}$ lies in the range of: