Question

A substance forms face-centered cubic crystals. Its density is 1.984 g/cm³ and the length of the edge of the unit cell is 630 pm. Calculate the molar mass in g/mol?

Options

• 149.35

• 74.65

• 29.85

• 18.66

Answer 1

74.65

Explanation:

M = `("d""N"_"A""a"^3)/("Z")`

= `(1.984 xx 6.02 xx 10^23 xx 25.0 xx 10^-23)/4`

= 74.65 g mol⁻¹