How many total constituent particles are present in a simple cubic unit cell?

If the radius of an anion is double that of a cation,the coordination number of the cation and the type of hole occupied are respectively:

Which of the following statements is incorrect for the rock salt type structure?

The unit cell of a $NaCl$ lattice:

The radius of the largest sphere which fits properly at the centre of the edge of a body-centered cubic $(BCC)$ unit cell is (Edge length is represented by $a$) (in $a$)

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: