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:

Which of the following expressions is correct in the case of a $CsCl$ unit cell (edge length '$a$')?

If the radius ratio is in the range of $0.732 - 1.000$,then the coordination number will be

What is the coordination number of a particle in $hcp$ structure?

Platinum crystallizes in a face-centered cubic $(FCC)$ crystal with a unit cell edge length $a$. The distance between nearest neighbour atoms is