Question

Calculate the molar mass of an element having density 2.8 g cm⁻³ and forms fcc unit cell.

[a³.N_A = 38.5 cm³ mol⁻¹]

Options

• 26.95 g mol⁻¹

• 23.5 g mol⁻¹

• 29.2 g mol⁻¹

• 21.6 g mol⁻¹

Answer 1

26.95 g mol⁻¹

Explanation:

For fcc unit cell, n = 4.

Density `(rho) = (Mn)/(a^3 N_A)`

`2.8 = (M xx 4)/38.5`

`M = (2.8xx38.5)/4`

= 26.95 g mol⁻¹