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Which of the following describes a compound? (hint: carbon and oxygen bo a. a piece of pure carbon, containing only carbon atoms b. oxygen gas surrounding a solid piece of carbon c. a substance made of two oxygen atoms for each carbon atom carbon and oxygen atoms mixed without being bonded together

Estimate the molar mass of the gas that effuses at 1.6 times the effusion rate of carbon dioxide.

Give one example of a pure (exact) number and of an estimated (measured) number.