Answer:-

Given: Type of unit cell is bcc.
Edge length (a) = 288 pm = 2.88 × 10^–8 cm,
Mass of element (x) = 200 g

To find:
i. Number of unit cells in 200 g of element

ii. Number of atoms in 200 g of element

Formulae:
i. Number of atoms in x g of element =x x n/(rho a³)

ii. Number of unit cells in x g of element = x/(rho a³)

Calculation:

i. For bcc unit cell, n = 2.

Using formula (i),

Number of atoms in 200 g of element

= (200 gx 2)/(14.44 g cm³x (2.88 xx 10^-8 cm³ ) ) = 1.16 x 10²⁴

ii. Using formula (ii),

Number of unit cells in 200 g element

= (200 g)/(14.44 g cm³x(2.88 x 10^-8 cm)^-3 ) = 5.80 x10²³

∴ Number of atoms in 200 g element is 1.16 × 10²⁴.

∴ Number of unit cells in 200 g element is 5.80 ×10²³.