What is the coordination number of a cation present in a tetrahedral void?

In a mineral $MX_2$,$M^{+2}$ ions are arranged in a $ccp$ structure and $X^{-}$ ions occupy the tetrahedral voids. What are the number of cations and anions per unit cell,the coordination number of the cation,and the percentage of occupied tetrahedral voids,respectively?

In a face-centered cubic lattice,a unit cell face is shared equally by how many unit cells?

In calcium fluoride,having the fluorite structure,the coordination numbers for calcium ion $(Ca^{2+})$ and fluoride ion $(F^{-})$ are

In a cubic structure,$W$ atoms are present at the corners of the unit cell,$O$ atoms are at the edge centers,and $Na$ atoms are at the center of the cube. What is the formula of the compound?

If $AgI$ crystallises in zinc blende structure with $I^{-}$ ions at lattice points,what fraction of tetrahedral voids is occupied by $Ag^{+}$ ions? ............ $\%$