What is the coordination number of the $Ca^{2+}$ ion in the fluorite structure?

The $FCC$ unit cell of a compound contains ions of $A$ at the corners and ions of $B$ at the centre of each face. What is the formula of the compound?

If the distance between $Na^{+}$ and $Cl^{-}$ ions in sodium chloride crystal is $X \ pm$, the length of the edge of the unit cell is

In a body-centered cubic $(BCC)$ unit cell,how many metal atoms surround the metal atom located at the center of the cell?

$A$ solid has a structure in which $W$ atoms are located at the corners of a cubic lattice, oxygen atoms at the edge centres, and $Na$ atoms at the body centre. The formula of the compound is:

For an ionic crystal of the type $AB$,the value of the limiting radius ratio is $0.40$. This value suggests that the crystal structure should be: