Which sample contains the greatest number of oxygen atoms?
44.0 g of CO244.0\text{ g of }\text{CO}_244.0 g of CO2
90.0 g of H2C2O4⋅2H2O90.0\text{ g of }\text{H}_2\text{C}_2\text{O}_4\cdot2\text{H}_2\text{O}90.0 g of H2C2O4⋅2H2O
72.0 g of H2O72.0\text{ g of }\text{H}_2\text{O}72.0 g of H2O
135 g of CaCO3135\text{ g of }\text{CaCO}_3135 g of CaCO3