Counting carbon atoms

Diamond, graphite and fullerene are all carbon, at $12\ \text{g}$ for every mole of atoms. You will count the atoms in samples of carbon, count the molecules in a sample of $\text{C}_{60}$, and find the atoms in a small diamond.

The idea. Atoms $=$ mass $\div 12\ \text{g/mol} \times N_A$. A molecule of $\text{C}_{60}$ has a molar mass of $720\ \text{g/mol}$.

Your tasks.

1. In atoms, return the number of carbon atoms in a mass of carbon, in grams.
2. In c60_molecules, return the number of $\text{C}_{60}$ molecules in a mass.
3. Find ring_atoms, the atoms in a diamond of $0.25$ carat. One carat is $0.2\ \text{g}$.