In an ionic crystal,ion $A$ is present at the corners of the cubic unit cell,and ion $B$ is present at the centers of the faces. What is the formula of this ionic compound?

The crystal structure of $AB$ is of $NaCl$ type. If the radius of the $A^+$ ion is $x \ pm$ and the radius of the $B^-$ ion is $y \ pm$, then the edge length of the unit cell will be ..........

The ratio of anion radius to cation radius of a crystal is $10 : 9.3$. Then, the coordination number of the cation in the crystal is

In a face-centered cubic lattice of $X$ and $Y$ atoms,$X$ atoms are present at the corners while $Y$ atoms are at the face centers. If two atoms of $X$ are missing from the corners,what is the formula of the compound?

The $8:8$ type packing is present in which of the following?

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