An ionic compound $AB$ has $ZnS$ type structure. If the radius of $A^{+}$ is $22.5 \ pm$, then the ideal radius of $B^{-}$ would be .............. $pm$.

For tetrahedral coordination number,the radius ratio $\frac{r_{c^+}}{r_{a^-}}$ is

$A$ compound is formed by elements $A$ and $B$. Atoms of $A$ are present at the corners of the cube,and atoms of $B$ are present at the body center. What is the formula of the compound?

An alloy of copper,silver,and gold is found to have copper atoms in an $fcc$ lattice. If silver atoms occupy the edge centers and gold atoms are present at the body center,what is the formula of the alloy?

What is the coordination number of any particle in the $fcc$ (face-centered cubic) crystal lattice?

An element crystallizes in a structure such that the unit cell is a cube with one atom at each corner and two atoms on its body diagonal. If the volume of this unit cell is $24 \times 10^{-24} \, cm^3$ and the density of the element is $7.2 \, g \, cm^{-3}$,calculate the number of atoms present in $200 \, g$ of the element.