How many atoms would be present in a black dot marked on the paper with graphite pencil as a full stop at the end of a sentence. [Given mass of a dot = 10- 18 g]

1 mole of carbon atoms weigh = 12 g

Also, 1 mole of carbon atoms = 6.022 x 10²³ atoms

Thus, 12 g of carbon atoms has 6.022 x 10²³ atoms.

∴ 10^{– 18} g of carbon will have 6.022𝑥10²³/12 x 10^{– 18} carbon atoms

                                                  = 5.02 × 10 ⁴ carbon atoms.