Answer: Chlorine
Explanation:
An independent variable can be define as changable variable, which can be used to determine it's impact over the other variable(s) in the experiment. Dependent variable cannot be changed manually instead changes occur in the independent variable is because of impact of independent variable. 
In this experiment, chlorine is the independent variable. The effect of which can be observed on the hair color, which is a dependent variable.
 
        
             
        
        
        
Answer:Higher levels of organization are built from lower levels. Therefore, molecules combine to form cells, cells combine to form tissues, tissues combine to form organs, organs combine to form organ systems, and organ systems combine to form organisms.
Explanation:
 
        
             
        
        
        
Concerns over a global dependence on fossil fuels include environmental, economic, and social consequences. 
the answer is True