H2+1/2O2-->H2O
since there are two atoms of hydrogen present in the reactants and in the product you don't need to add any number before H2
we add 1/2 before O2 because only 1 atom is needed for the water molecule
 
        
                    
             
        
        
        
Answer: The nucleus
Explanation: It directs the cell's activities in the plant and animal cells.
 
        
             
        
        
        
Hutton: created the idea that a (water erosion basically)continuing process formed and destroyed the rocks and soils of the Earth and that the process was a never ending loop. 
Hutton laid the conceptual foundation for uniformitarianism geology
Lyell: added names and ages to the different layers of rocks
Lyell built the structure of geology upon that foundation
        
             
        
        
        
Charles Darwin made the observations which led to the theory of evolution.