Where #N_A-=6.022xx10^23*mol^-1#....
In each mole of glucose, i.e. in each #6.022xx10^23# individual glucose molecules, there are CLEARLY #6*mol# of oxygen atoms, #12*mol# of hydrogen atoms, and #6*mol# of carbon atoms... Do you appreciate this? Here I use the mole as I would ANY OTHER collective number, i.e. #"dozen"#, #"gross"#, or #"half-dozen"#.
Why do we use such an absurdly large number? Well, because #1*mol# of #""^12C# atoms has a mass of #12*g#; #1*mol# of #""^16O# atoms has a mass of #16*g#; and #1*mol# of #""^1H# atoms has a mass of #1*g#. The mole is thus the link between the micro world of atoms, and molecules, which we certainly cannot see, but whose existence we can infer, with the macro world or grams, and kilograms, and pounds, and litres, etc, the which we can measure out by some means in a laboratory.......
So what is the mass of the given molar quantity of oxygen atoms?