How many moles of o2 are needed to create 9 mol of co2 gas

18 molecules of oxygen or o2

Explanation:

Because a carbon dioxide molecule has 2 oxygen molecules and 1 carbon molecule, this would mean that, to make 9 co2 molecules, you would need

18 because 9x2 is 18 molecules of 02

and for carbon molecules its literally 9 because for just 1

co2 it contains 1 carbon molecule

hope this helped

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.