The best substance to heat up the fastest would be blue fire
        
                    
             
        
        
        
Let x represent the total distance around the track
Jason's distance: (5/7)x
Sara ran (4/5) of Jason's distance, 
so she ran (4/5)*(5/7)x = (4/7)x
Sara ran 4/7 of the total distance
        
             
        
        
        
Answer: One formula unit of NaCl consists of one cation, whose chemical symbol is  and one anion whose chemical symbol is
 and one anion whose chemical symbol is 
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.  
The cation is formed by the metal sodium which forms   and the anion is formed by non metal chlorine which forms
 and the anion is formed by non metal chlorine which forms  .
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For a formula unit of sodium chloride,  the charges have to be balanced , thus the valencies of ions are exchanged and the neutral compound result. Thus 
  and
 and   combine to form neutral
 combine to form neutral 
 
        
             
        
        
        
Answer:
yes your answer is correct for this question.
 
        
             
        
        
        
They all just formed on top of each other like sedimentary rocks