Answer: 26.75 meters.
2πr = 84
2 * 3.14 * radius = 84
radius = 84/6.28
r= 13.375 
So the diameter will be 13.375 + 13.375 which is 26.75 meters.
 
        
             
        
        
        
Answer:
Rigid Structure i think...
Explanation:
Plant cells contain a cell wall which contributes to the <u>rigid</u> structure it obtains.
 
        
                    
             
        
        
        
Answer:
Hydrogen, Lithium, Aluminum, Argon, Nickel, Iodine, Gold, Mercury
  
Explanation:
Hydrogen has 1 proton.
Lithium has 3 protons.
Aluminum has 13 protons.
Argon has 18 protons.
Nickel has 28 protons.
Iodine has 53 protons.
Gold has 79 protons.
Mercury has 80 protons.
Hope this helps.