the unconditional guru

1 molecule of H₂O has 1 atom of oxygen.

Firstly we will calculate the number of atoms in 90g of H2O.

we will explain it in two steps:-

Step I:-

No.of moles of H₂O = given mass / molar mass

No. of moles = 90/18 = 5 moles

No. Of molecules = No. of moles x Avogadro number

=5 x 6.022×10²³

Step II :-

1 molecule has = 1 oxygen atom

So the number of atoms of oxygen = number of molecules of water

No. of oxygen atoms = number of H2O molecules

No. of oxygen atoms = 30.11 x 10²³