This problem is providing us with the mass of calcium and chlorine. Thus, the percent composition of each element in the compound is required and found to be 36 % for calcium and 64 % for chlorine, according to the following:
In chemistry, we can use percent compositions in order to find a relationship between the relative amount of the elements in a compound and the mass of the very same compound.
In this case, given the mass of each element (chlorine and calcium), one can simply divide it by the sum of the masses of both calcium and chlorine to obtain the following:
[tex]\% Ca=\frac{16.2g}{16.2g+28.8g}*100\%= 36\%\\\\\% Ca=\frac{28.8g}{16.2g+28.8g}*100\%= 64\%\\[/tex]
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