Independent variable would be salt since you can't change it in this experiment. 
 
        
             
        
        
        
Answer:
Earth's atmosphere contains a huge pool of nitrogen gas (N2). But this nitrogen is “unavailable” to plants, because the gaseous form cannot be used directly by plants without undergoing a transformation. To be used by plants, the N2 must be transformed through a process called nitrogen fixation.
 
        
             
        
        
        
Answer:The atom being mostly empty space. A small number of alpha particles were deflected by large angles (> 4°) as they passed through the foil. There is a concentration of positive charge in the atom. Like charges repel, so the positive alpha particles were being repelled by positive charge
 
        
             
        
        
        
Answer:
A wave pattern organizes a speech