An element M crystallises in a body centred cubic unit cell with a cell edge of 300 pm . The density of the element is 6 . 0 g cm - 3 . The number of atoms present in 180 g of the element is____ × 10 23 . (Nearest integer)

Step-by-step solution

M is body centred cubic, ∴   Z = 2 Let mass of 1 atom of M is A Edge length = 300 pm Density = 6   g / cm 3 ∴   6   g / cm 3 = Z × A 300 × 10 - 10 3 = 2 × A 27 × 10 - 24 A = 81 × 10 - 24   g Atoms of M = T o t a l   m a s s M a s s   o f   o n e   a t o m   =   180 81 × 10 - 24   =   22 . 22 × 10 23 ≅ 22 × 10 23