Which of the following exhibits an $8:8$ coordination type packing?

The number of unit cells present in $39 \ g$ of potassium if it crystallizes as a body-centered cubic $(BCC)$ structure is ($N = \text{Avogadro number}$, $\text{At. wt. of potassium} = 39$).

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:

The volume occupied by all the particles in a $B.C.C.$ unit cell is

If an atom is present in the centre of the cube,the participation of that atom per unit cell is

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