In the $NaCl$ crystal structure,how many chloride ions surround each sodium ion?

The unit cell of a binary compound of $A$ and $B$ metals has a $ccp$ structure with $A$ atoms occupying the corners and $B$ atoms occupying the centres of each face of the cubic unit cell. If during the crystallisation of this alloy,two $A$ atoms are missing from the unit cell,the overall composition per unit cell is:

What is the number of atoms present in the unit cells of a simple cubic,body-centered cubic,and face-centered cubic lattice of a monoatomic substance,respectively?

In sodium chloride,$Cl^-$ ions form a $ccp$ arrangement. In this structure,where are the $Na^+$ ions located?

What is the coordination number of each sphere in a two-dimensional hexagonal close-packed structure?

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?