If the cation is present in the tetrahedral void,what is the radius ratio ${r_ + }/{r_ - }$?

The intermetallic compound $LiAg$ crystallizes in a cubic lattice in which both lithium and silver have a coordination number of $8$. The crystal class is

If all ions touching an axis passing through two opposite face-centres of unit cell are removed in $NaCl$ (rock salt) structure in which $Cl^{-}$ ions form $CCP$ and $Na^{+}$ ions occupy all octahedral voids,then the effective number of $Cl^{-}$ ions per unit cell is:

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

An ionic compound has unit cells consisting of $A$ ions at the corners of a cube and $B$ ions on the centres of the faces of the cube. The empirical formula of this compound is

$A$ compound formed by elements $A$ and $B$ crystallizes in a cubic structure where $A$ atoms are at the corners of the cube and $B$ atoms are at the center of the cube. What is the formula of the compound?