By the heat of the enegry
        
             
        
        
        
Answer:
The answer is A
Explanation:
It is logical because the balloon lets the student see how much gas is released in the reaction. the balloon inflates with invisible air the student will normally not see.
 
        
                    
             
        
        
        
Answer:
Skin cancer refers to the abnormal activity of skin cells associated with carcinogenesis
Explanation:
This disease is associated with the DNA damage (mutations) often caused by  the irrational exposition to UV sun rays that trigger DNA mutations capable of both inactivating tumor suppresor genes and activating oncogenes