ANSWERS: 1

First identify what elements and how many are there: 18 x Carbon 21 x Hydrogen 1 x Nitrogen 3 x Oxygen Now work out what mass of each element is there: Carbon: 18 x 12 (atomic weight) = 216 Hydrogen: 21 x 1 = 21 Nitrogen: 1 x 14 = 14 Oxygen: 3 x 16 = 48 Now work out the total mass of the molecule: 216 + 21 + 14 + 48 = 299 Now work out what % the Oxygen has of this weight: 48 / 299 x 100 = 16% Note: these numbers came from the top of my head and it has been a while since I studied them so they may be wrong, but I dont think so. Also the accuracy of the atomic masses will need to be adjusted to represent the level of the study. But this is the basi method used for the problem.
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