If 150 G of wood started Burning, and 30 G of wood ash was left behind, how many grams of CO2 to gas was released

120G

Explanation:

From the combustion process, about 120G of carbon dioxide would be released into the atmosphere.

For the chemical reaction to obey the law of conservation of matter, if only ash and carbon dioxide are the product, then the sum of the mass of the product and that of the reactants must be the same.

   In a chemical reaction, matter is not created nor destroyed, but they are simply changed from one form to another.

   Mass of wood burning  = mass of ash + mass of CO₂

              150G  = 30G + mass of CO₂

         mass of CO₂ = 150G  - 30G  = 120G

the answer to this question is 3.