C, they could work together to make things from the top down.
The third answer because there are two of each atom
I believe your answer would be helium friend :)
At STP one mole of any gas occupies 22.4 L
moles NO2 = 99.0/22.4 = 4.42
mass NO2 = 4.42 mol x 46.0 g/mol=203 g
its A plant like protist produce oxygen ...