The radius of $Na^{+}$ is $95 \, pm$ and the radius of $Cl^{-}$ ion is $181 \, pm$. What is the coordination number of $Na^{+}$?

An alloy of gold and copper crystallizes in a cubic lattice in which the gold atoms occupy the lattice points at the corners of a cube and copper atoms occupy the centers of each of the cube faces. Determine the formula of this compound.

In the rock salt structure,the number of formula units per unit cell is equal to

If three elements $X$,$Y$ and $Z$ crystallise in a $ccp$ lattice with $X$ atoms at the corners,$Y$ atoms at the cube centre and $Z$ atoms at the edges centre,the formula of the compound will be

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:

Gold has a face-centred cubic $(fcc)$ lattice with an edge length of the unit cube of $407 \ pm$. Assuming the closest packing, the diameter of the gold atom is .............. $pm$.