Potassium crystallizes in a $bcc$ lattice,hence the coordination number of potassium in potassium metal is

Consider an ionic solid $MX$ with $NaCl$ structure. Create a new unit cell $(Z)$ from the unit cell of $MX$ by following the sequential instructions given below. Ignore charge balance.
$(i)$ Remove all anions $(X)$ except the central one.
$(ii)$ Replace all face-centered cations $(M)$ with anions $(X)$.
$(iii)$ Remove all cations $(M)$ at the corners.
$(iv)$ Replace the central anion $(X)$ with a cation $(M)$.
The value of $\left(\frac{\text{number of anions}}{\text{number of cations}}\right)$ in $Z$ is . . . . .

$A$ compound $M_pX_q$ has a cubic close packing $(ccp)$ arrangement of $X$. Its unit cell structure is shown below. The empirical formula of the compound is

$CsBr$ crystal has $bcc$ structure. It has an edge length of $4.3 \ \mathring{A}$. The shortest interionic distance between $Cs^{+}$ and $Br^{-}$ ions is ................ $\mathring{A}$.

The number of $Cl^{-}$ ions around one $Na^{+}$ in $NaCl$ crystal lattice is

In an $NaCl$ crystal,how many $Cl^{-}$ ions surround each $Na^{+}$ ion?