Yes , i would help you but the photo isn't clear . :(
        
             
        
        
        
LD50 is used to express TOXICITY OF TOXINS AND POISONS.
LD50 stands for Lethal Dose 50. This is the standard measure of the toxicity of a material, which will kill half of the sample population of a particular test animal in a defined time period, when they are exposed to the material.
        
                    
             
        
        
        
Answer:
Fluoride theoretically should have 8
Explanation:
Fluoride is the Fluorine ion, meaning electrons are added or substracted from Fluorine to form Fluoride. Usually, an ion has a full outer shell. 
 
        
             
        
        
        
All of the above are carbon link.