Answer:burning of fossil fuels and the decrease of oxygen and the increase of carbon dioxide
Explanation:
 
        
                    
             
        
        
        
Answer:
Natural chemicals are produced by nature without any human intervention. Synthetic chemicals are made by humans using methods different than those nature uses, and these chemical structures may or may not be found in nature. Stay safe .
 
        
                    
             
        
        
        
yes substances Do  react by mass
 
        
             
        
        
        
Answer:
Look at your periodic table
Explanation:
It tells you everything like Potasium 1 and 1 ox and 1 hydrogen
 
        
             
        
        
        
Answer:
Energy
Explanation:
A sugar group would be used for carbohydrates or nucleic acids. An adenosine group would be used in ATP formation if I recall correct. And disaccharides are just two monosaccharides linked together, so that would also be for carbohydrates. Therefore, energy is the answer.