4.42 
Because when you divide 129/29.20, you get a long string of numbers. 4.417808219178082...
So you round to the significant figure which in this case is 2 decimal places because 29.20 has 2 decimal places. 
PS did you draw that car? Cuz im into drawing cars too.
 
        
             
        
        
        
Explanation:
Given elements: 
   F, Sr, P, Ca, O, Br, Rb, Sb, Li, S
Elements with the same chemical reactivity will belong to the same group on the periodic table. This implies that elements in the same column will have the same reactivity; 
   Li and Rb are both alkali metals in group 1
   Ca and Sr are both alkali earth metals in group 2 
   F and Br are halogens in group 7 
   O and S are group 6 elements 
  P and Sb are both in group 5 on the periodic table 
So these groupings show elements with the same chemical properties. 
 
        
             
        
        
        
Hi, you've asked an incomplete question. However, I assumed you are referring to the article found on the Scientific American website.
Explanation:
<em>Remember,</em> according to that article we are told that scientists notice that these insects have a long nymphal (immature form before becoming adults) stage, one that can last up to 13 to 17 years on the ground before they leave the ground looking for mating partners.
Because it is only after mating occurs at this point that their eggs are laid, that is why scientists believe that cicadas only reproduce every 13 or 17 years.
 
        
             
        
        
        
<span>At room temperature and atmospheric pressure, nothing happens when the two gasses are mixed. However, at high temperature and pressure (450C, 200atm), in the presence of an iron oxide catalyst, the production of ammonia is thermodynamically advantageous.</span>
        
             
        
        
        
<span>Li2O2 is the formula
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