The answer is           
e o i and a
not really sure forgive me if im wrong
        
             
        
        
        
The difference in the concentration of a substance between two areas is called the concentration gradient. When a region has a higher particle concentration than another, this is known as a concentration gradient. A concentration gradient will cause particles in passive transport to diffuse down it from higher concentration to lower concentration until they are evenly spaced. 
The gradual separation of a region of high density from a region of low density in a solution in terms of the concentration of a dissolved material. Understanding how ions and particles flow randomly in a solution or gas depends on the concentration gradient. 
To learn more about concentration, click here.
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Answer:
Mn (s) + NiCl2 (aq) → MnCl2 (aq) + Ni
Explanation:
The order of displacement of metals from aqueous solution by another metal is defined by the activity series of metals. 
The activity series arranges metals in order of reactivity and increasing electrode potentials. The less negative the electrode potential of a metal is, the less reactive it is and the lower it is found in the activity series.
Nickel has a less negative electrode potential than manganese hence it is displaced from an aqueous solution of its salt by manganese spontaneously.
 
        
             
        
        
        
You would calculate them by dividing them and then multiplying to get the final answer
        
             
        
        
        
It has a pb of 69c from google