Obi is trying to determine if a powdery, solid substance is an element or a compound. after recording some observations, he strongly heats a sample of the solid over a burner flame. after fifteen minutes, he turns off the flame and allows the sample to cool. he records his final observations in the data table. which is the best explanation of his results?

The chemical reaction with acid changed, showing that the sample was broken down by heating. Therefore, the original substance is a compound.

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its not a choice. you dont choose if you want to be gay or straight.

in theory, limestone is composed principally of the compound calcium carbonate - caco3, but in reality this compound is deposited in conditions involving a number of other compounds as impurities so it ends up being a mixture of many compounds.

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tony (lordcaos066)