What is the molar mass of just the O in CO2?

16 g/mol

Explanation:

In CO2, it means we have 1 mole of carbon and 2 moles of oxygen.

However, we want to find the molar mass of just a single mole of oxygen.

Now, from tables of values of elements in electronic configuration, the molar mass of oxygen is usually approximately 16 g/mol.

In essence the molar mass is simply the atomic mass in g/mol

gasoline is a mixture. it contains several different kinds of compounds that can be present in a variety of ratios.