What is the mass by precent of oxygen in carbon dioxide (co2)

Oxygen has a molar mass of 16.0 g mol−1 , so 1 mole of oxygen atoms has a mass of 16.0 g . Therefore, carbon dioxide has a percent composition of 72.7% oxygen, i.e. for every 100 g of carbon dioxide you get 72.7 g of oxygen

Explanation:

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.