The answer is "A. a pure substance can be separated by chemical means, while a mixture can be separated by physical means". A pure substance only has one type of substance, whereas a mixture has more than one. A pure substance therefore, can only be separated chemically, because it is not two things mixed together, whereas a mixture can be separated physically because there are multiple substances.
Silicate. It is silica, SiO2 with contaminants such as Fe3+ that give it color. technically it is a tecto-silicate.<span>
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Explanation:
Molar mass of O2: 32g/mol
Moles of O2 = 19.5 / 32 = 0.609mol
