Question

Which of the following elements has the largest interatomic distance in its solid form? Select one:

a. Rb

b. Sn

c. Sb

d. Te

e. Se

Answer 1

The interatomic distances in solid form is nothing but twice the radius(2R_i) of the respective atom in consideration:

So first we need to know which of the given elements have largest radius

The following points needed to be noted:

1. Going from left to right in a period, the atomic radii decrease with increased nuclear attraction
2. Going from top to bottom, the atomic radii increases due to additional orbitals added

So with the facts above, out of all, except Se, all others belong to same peroid. And Se is just above Te, which makes it smaller than Te.
And Rb is the First group element. So will be having highest atomic radius, and correspondingly it have largest Interatomic distance also.