People who work with radioactive materials often wear a film badge to reveal how much radiation they have been exposed to. The film badge dosimeter or the film badge is a dosimeter worn by these people working with materials that are radioactive for the purpose of monitoring cumulative radiation dose due to ionizing radiation. The badge has two parts; the photographic film, and a holder.  
        
                    
             
        
        
        
Answer:
Option A. 
2Na + 2H2O —> 2NaOH + H2 
Explanation:
To know which option is correct, we shall do a head count of the number of atoms present on both side to see which of them is balanced. This is illustrated below below:
For Option A:
2Na + 2H2O —> 2NaOH + H2
Reactant >>>>>>> Product
2 Na >>>>>>>>>>> 2 Na
4 H >>>>>>>>>>>> 4 H
2 O >>>>>>>>>>>> 2 O
Thus, the above equation is balanced. 
For Option B:
2Na + 2H2O —> NaOH + H2
Reactant >>>>>>> Product
2 Na >>>>>>>>>>> 1 Na
4 H >>>>>>>>>>>> 3 H
2 O >>>>>>>>>>>> 1 O
Thus, the above equation is not balanced.
For Option C:
2Na + H2O —> 2NaOH + H2
Reactant >>>>>>> Product
2 Na >>>>>>>>>>> 2 Na
2 H >>>>>>>>>>>> 4 H
1 O >>>>>>>>>>>> 2 O
Thus, the above equation is not balanced. 
For Option D:
Na + 2H2O —> NaOH + 2H2
Reactant >>>>>>> Product
1 Na >>>>>>>>>>> 1 Na
4 H >>>>>>>>>>>> 5 H
2 O >>>>>>>>>>>> 1 O
Thus, the above equation is not balanced. 
From the illustrations made above, only option A is balanced.
 
        
             
        
        
        
<span>the elements in groups1a, 2a, 3a have positive charges according to their group numbers</span>
        
             
        
        
        
Answer:
synergistic
Explanation:
Synergistic means: relating to the interaction or cooperation of two or more organizations, substances, or other agents to produce a combined effect greater than the sum of their separate effects
 
        
             
        
        
        
The question is incomplete, here is the complete question:
There are two steps in the usual industrial preparation of acrylic acid, the immediate precursor of several useful plastics. In the first step, calcium carbide and water react to form acetylene and calcium hydroxide:
  
In the second step, acetylene, carbon dioxide and water react to form acrylic acid:  
  
Write the net chemical equation for the production of acrylic acid from calcium carbide, water and carbon dioxide. Be sure your equation is balanced.
<u>Answer:</u> The net chemical equation is written below.
<u>Explanation:</u>
The intermediate balanced chemical reaction are:
(1)  
     ( × 6 )
(2)  
  
To omit acetylene from the net chemical reaction, we multiply Equation (1) by 6.
<u>Equation 1:</u>  
<u>Equation 2:</u>  
  
<u>Net chemical equation:</u>   
Hence, the net chemical equation is written above.