Hey, the two answers that would best fit in the blank would be B.) reproduce by mitosis & D.) Have 46 chromosome pairs. 
Sentence form: Skin cells reproduce by mitosis and have 46 chromosome pairs. 
 
        
             
        
        
        
B) the number of electrons
        
                    
             
        
        
        
Use the formula for second order reaction:

C = concentration at time t 
C0 =  initial conc.
k = rate constant
t = time
1st equation :   

2nd Equation: 

Find 

 from 1st equation and put it in 2nd equation:


k = 0.046
 
        
        
        
Answer:
Nickel is the answer
Explanation:
Lol that's easy the atomic number is the same number as the number of electrons.