How many moles are in 8.6 g of CO2?

A mole of a substance contains a molar mass of that substance. The molar mass of a substance is equal to the mass of all the atoms contained in a mole of that substance.

For example, carbon dioxide consists of carbon and oxygen. More specifically, each molecule of carbon dioxide contains 1 atom of carbon and 2 atoms of oxygen. Since, carbon has an atomic mass of 12 g per mole and oxygen has an atomic mass of 16 g per mole, the molar mass of carbon dioxide is 44 g per mole (= 12 + 2 x 16).

That is, one mole of carbon dioxide contains 44 g of carbon dioxide. Here, we have only 8.6 g carbon dioxide. Thus, the number of moles in 8.6 g carbon dioxide are equal to 

8.6 g / 44 g/mole = 0.1955 mole or about 0.2 moles.

Hope this helps.