Question

How many carbon atoms are there in a diamond (pure carbon) with a mass of 52 mg?

Answer 1

Note:
A unit cell of diamond has 8 carbon atoms and has a volume of 10⁻²¹ cm³.
Carbon diamond has a density of about 3.52 g/cm³

Therefore the number of atoms in a carbon diamond with a mass of 52 mg is
$( \frac{8 \, atoms}{10^{-21} \, cm^{3}} )*( \frac{1 \, cm^{3}}{3.52 \, g} )*(52 \times 10^{-3} \, g) = 1.182 \times 10^{20} \, atoms$

Answer: 1.182 x 10²⁰ atoms