Which compound has the highest percent composition by mass of strontium?

Assuming all the compounds of interest are given. We proceed on the theoretical way of answering this question. Assume 1 gram of each compound. Multiply it by the reciprocal of the molar mass of the compound. Then multiply it by the molar ratio of the Strontium to the compound. Then, multiply it by the molar mass of strontium. Finally divide this answer by 1 gram and multiply by 100. 

Just took the quiz on edgenuity and the correct answer is "c.  4.54 x  10–12  j"

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