Calculate the mass of `1.2044 xx 10^(23)` molecules of `O_(2) ("Atomic mass of O"=16u)`.

Explanation

`6.022 xx 10^(23) (N_(A))` molecular of `O_(2)` have mass = 32 u
`1.2044 xx 10^(23)` molecular of `O_(2)` have mass `=((32u) xx (1.2044 xx 10^(23)))/((6.022 xx 10^(23))) = 6.4 u`