What is the mole fraction of carbon dioxide in a mixture consisting of equal masses of CO2 (MW=44) and neon (MW=20.2)?

Endeleev saw trends in the physical and chemical properties of elements when he organized them by

Plz choose one of the compounds from the table and explain how you know the numbers of atoms in your formula. is it possible for two different compounds to be made from the exact same two elements? why or why not? with a limited number of elements (less than 120 are known), does this mean we also have a small number of compounds or do we have a large number of compounds in this world?

Using the periodic table, complete the table to describe each atom. type in your answers