What is the molecular formula of a compound containing 89% cesium (Cs) and 11% oxygen (O) with a molar mass = 298 g/mol?

M (Cs) = 133 g/mol

M (O) = 16 g/mol

M (CsxOy) = 298 g/mol

w (Cs) = 0.89

w (O) = 0.11

CsxOy

x=M (CsxOy) w (Cs) / M (Cs)

x=298*0.89/133=2

y=M (CsxOy) w (O) / M (O)

y=298*0.11/16=2

Cs₂O₂ cesium peroxide