Answer:
i am pretty sure the answer is a
Explanation: because the airplane's flight time has to be the independent variable for it to affect the dependent variable that is the speed of how fast the airplane is going. 
 
        
                    
             
        
        
        
Answer:
Erosion
Explanation:
Erosion is not a cause of metamorphism 
The causes are mostly temperature, pressure, heat from the metamorphic rock
 
        
                    
             
        
        
        
Answer:
The chemical equation needs to be balanced so that it follows the law of conservation of mass.
Explanation:
 
        
                    
             
        
        
        
Answer: B. Hydrolysis (adding water)
Explanation:
When peptide bonds join two or more amino acids together, this is refered to as a peptide. A polypeptide simply means several amino acids. We should also note that proteins contains polypeptides. 
The reaction that is capable of breaking polypeptides into their component amino acids is hydrolysis. This simply means a chemical process whereby a water molecule is being added to a particular substance.