The graphite present in a pencil weighs is 140 mg. Calculate the number of carbon atoms in it.

Explanation

Atomic mass of carbon = 12
12 g of carbon contains `=6.022 xx 10^(23)` atoms.
0.140 g of carbon contains = ? Atoms
Number of carbon aromas in 0.140 g `=(0.140 xx 6.022 xx 10^(23))/12`
`=7.025 xx 10^(21)`