What is the coordination number in a hexagonal close-packed $(h.c.p.)$ structure?

$A$ binary compound $(A^{+} B^{-})$ has a zinc blende structure where $B^{-}$ ions form the lattice and $A^{+}$ ions occupy $25\%$ of the tetrahedral voids. What is the formula of the compound?

What is the coordination number of each atom in a $bcc$ structure?

In a $ccp$ lattice of $X$ and $Y$,$X$ atoms are present at the corners while $Y$ atoms are at face centers. What would be the formula of the compound if one of the $X$ atoms from a corner is replaced by a $Z$ atom?

What is the total number of particles present in a base-centred unit cell?

For an ionic crystal with the general formula $AX$,the coordination number is $6$. What is the radius ratio range?