For a tetrahedral structure,the limiting radius ratio $r_c^+ / r_a^-$ is .......

Which of the following metals has a $ccp$ crystal structure?

In the crystal of $CsCl$,the nearest neighbours of each $Cs^+$ ion are

How many "nearest" and "next nearest" neighbours,respectively,does potassium have in a $bcc$ lattice?

For $bcc$ cubic coordination the value of radius ratio is

In a cubic structure of a compound made from $X$ and $Y$,where $X$ atoms are at the corners of the cube and $Y$ atoms are at the face centers of the cube,the molecular formula of the compound is: