How many atoms are there in a cube-based unit cell,having one atom on each corner and $2$ atoms on each body diagonal of the cube?

In an $NaCl$ crystal,how many $Cl^{-}$ ions surround each $Na^{+}$ ion?

$A$ cubic solid is made of two elements $P$ and $Q$. Atoms of $Q$ are at the corners of the cube and $P$ at the body-centre. What is the formula of the compound? What are the coordination numbers of $P$ and $Q$?

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

What is the mass of an $fcc$ unit cell if the mass of one atom of an element is $6 \times 10^{-23} \ g$?

$A$ compound made of elements $A$ and $B$ forms an $fcc$ structure. Atoms of $A$ are at the corners and atoms of $B$ are present at the centres of the faces of the cube. What is the formula of the compound?