Answer
c. 87% Cesium, 13% Fluorine
Explanation
From the periodic table, the atomic masses of F = 18.998403 g/mol and Cs = 132.90545 g/mol.
So the molar mass of CsF = 132.90545 + 18.998403 = 151.903853 g/mol
[tex]\begin{gathered} Percent\text{ }composition\text{ }of\text{ }Cesium=\frac{Atomic\text{ }mass\text{ }of\text{ }Cs}{Molar\text{ }mass\text{ }of\text{ }CsF}\times100\% \\ \\ Percent\text{ }composition\text{ }of\text{ }Cesium=\frac{132.90545}{151.903853}\times100\%=87\% \end{gathered}[/tex][tex]\begin{gathered} Percent\text{ }composition\text{ }of\text{ }Fluorine=\frac{Atomic\text{ }mass\text{ }of\text{ }F}{Molar\text{ }mass\text{ }of\text{ }CsF}\times100\% \\ \\ Percent\text{ }composition\text{ }of\text{ }Cesium=\frac{18.998403}{151.903853}\times100\%=13\% \end{gathered}[/tex]Therefore, the percent composition of Cesium and Fluorine in CsF is 87% Cesium, 13% Fluorine
