What is the mass of 12.04×10²³ atoms of O?

Question

Quizplus · Accepted Answer

1 mole of oxygen atoms has a mass of 16 g (this is the molar mass of oxygen). Therefore, 12.04×10²³ atoms of oxygen (which is 0.2 mol of oxygen atoms) have a mass of: 0.2 mol x 16 g/mol = 3.2 g However, we need to pay attention to significant figures. The given number, 12.04×10²³, has 4 significant figures, so our answer should also have 4 significant figures. Therefore, we should round 3.2 g to 3.20 g. Thus, the mass of 12.04×10²³ atoms of O is 3.20 g, which is closest to option C, 32 g.

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