The Total solution for NCERT class 6-12
Niobium crystallises inbody-centred cubic structure. If density is 8.55 g cm−3, calculate atomic radius of niobium using its atomic mass 93 u.
It is giventhat the density of niobium, d = 8.55 g cm−3
Atomic mass, M = 93 gmol−1
As the lattice is bcctype, the number of atoms per unit cell, z = 2
We also know that, NA = 6.022 × 1023 mol−1
= 3.612 × 10−23 cm3
So, a =3.306 × 10−8 cm
For body-centred cubicunit cell:
= 1.432 × 10−8 cm
= 14.32 × 10−9 cm
= 14.32 nm