Question

if one mole of Oxygen atoms weighs 16 gram find the mass of one atom of Oxygen in grams​

Answer 1

One mole (not one molecule) of oxygen atoms would weigh 16 g, because an oxygen atom weighs 16 u. To get the mass of an oxygen atom in grams, you'd divide 16 g/mol (well actually 15.999) by Avogadro's number, 6.022×10²³ /mol.

Answer 2

Mass of 1 mole atoms=16 gm

i.e. mass of 6.022*10^23. atoms= 16gm

so mass of 1 atom = 16÷6.022*10^23 = 2.6 *10^-23