Question

Second nearest neighbour in CsCl solid

ans: 6

how the answer came

I want step by step detailed explanation

Answer 1

The CsCl is an ionic structure showing two interpenetrating simple cubic lattices, one for each kind of ion. It has a coordination number 8.
There are six ions of the same charge from a given ion at a distance of ∛r where r is the distance between the anion and cation (e.g., rCs^+ + rCl^-). From diagram there are six ions of opposite charge in next-nearest contact, directly through the six faces of the cube at a distance of a where a is the side of the unit cell.
From Pythagoras the body diagonal of the unit cell is ∛a = 2r hence a = (2/∛ r) = 1.15r