If the edge length of a cubic unit cell is $a$,then the octahedral void is located at a distance of ....... from the corner of the cube.

$A$ compound is formed by elements $A$ and $B$. Element $A$ occupies the corners of the cube,and element $B$ occupies the face centers. What is the formula of the compound?

In a face-centered cubic $(FCC)$ arrangement,atoms $A$ are present at the corners and atoms $B$ are present at the face centers. If $4$ atoms of $A$ are removed from the corners,what is the empirical formula of the compound?

The structure of $TlCl$ is similar to $CsCl$. What would be the radius ratio in $TlCl$?

The structure of $MgO$ is similar to that of $NaCl$. What is the coordination number of $Mg^{2+}$?

$Na$ 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