Quiz on Science
1. What keeps the water in swimming pools clean?
      
       
     Oxygen 
 
 
       
     Chlorine 
 
 
       
     Fluorine 
 
 
       
     Boron 
 
 
    
 
     Oxygen 
 
 
       
     Chlorine 
 
 
       
     Fluorine 
 
 
       
     Boron