There are two moles of oxygen in one mole of sulfur dioxide, hence the molecular formula being SO2. Therefore, the number of oxygen moles will be double the number of moles of sulfur dioxide.
In sulphurdioxide, there is presence of 2 atoms of oxygen (O2). Therefore to get the total number of moles of oxygen in 3moles of SO2, we will multiply the number of atom of oxygen present (2) with the number of moles of SO2 compound (3).
That will be equivalent to 2×3 = 6moles of oxygen.
