What is the coordination number of each atom in $hcp$ or $ccp$ structure?

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 a mixed oxide of two metals $X$ and $Y$,divalent $X^{2+}$ ions occupy $50\%$ of the tetrahedral voids,while trivalent $Y^{3+}$ ions occupy $50\%$ of the octahedral voids. The formula of the oxide is:

In a face-centered cubic arrangement of $A$ and $B$ atoms,$A$ atoms are at the corners of the unit cell and $B$ atoms are at the face centers. If one of the $B$ atoms is missing from one of the faces in the unit cell,the simplest formula of the compound is:

Which of the following is a $1:2$ type compound?

Which type of cubic lattice has the maximum number of atoms per unit cell?