A solid having density of 9 × 10³ kg/m³ forms face centred cubic crystals of edge length 200√2 pm. What is the molar mass of the solid?

The correct option is A (0.0305 kg/mol)

Formula for density:

Density, d = Z × M / (a³ × NA)

where,
d = density of the unit cell
M = Molar mass of the molecule
a³ = volume of the unit cell
NA = Avogadro number

Here, for FCC unit cell, Z = 4

Substituting the values we get,

9 × 10³ = 4 × M / ((200√2 × 10⁻¹² m)³ × 6.0 × 10²³)

=> M = 0.0305 kg/mol