$A$ compound crystallizes in a $NaCl$ type structure. What is the percentage of unoccupied tetrahedral voids?

If the pressure on a $NaCl$ structure is increased,then its coordination number will

In a compound $AB$, $A$ atoms occupy the corners of the cube and the $B$ atoms occupy the body centre of the cube. If the $A$ atoms possess magnetic moment due to up-spin and $B$ atoms possess magnetic moment due to down-spin, the magnetic nature of the compound $AB$ in an isolated unit cell is

What is the total number of unit cells shared by each corner particle of a $bcc$ unit cell?

What is the coordination number of a particle in $hcp$ structure?

The crystal structure of $NaCl$ is: