Answer:
When the air pressure in the throat and outside the body is less than the air pressure in the middle ear, barotrauma occurs.
Explanation:
Ear barotrauma is a medical condition that describes discomfort in the ear which is caused by pressure differences in the inner and outer ear drum.
Usually, the air pressure in the middle ear is the same as the air pressure in the throat and outside the body. 
When we swallow, the eustachian tube opens up and air flows out of and into the middle ear, this balances the pressure. But if the eustachian tube is blocked, the air pressure in the throat and outer body become different from the air pressure in the middle ear.
 
        
             
        
        
        
Answer:
Fluorine is the most reactive element
 
        
                    
             
        
        
        
The equation is 
s= d/t
In this case you would have to write it out as:
s= 20/5
Speed = 4
        
             
        
        
        
Answer:
Explanation:
Speed and medium are properties of a wave which is in common within an area of the spectrum of visible light. i.e;
Their medium of propagation
They both travel at the same speed ( speed of light )
The properties mentioned above are properties that define that wave is found within an area spectrum for visible light.
 
Wish I Could Help You!
 
        
             
        
        
        
Well it determines on how much  magnetism a material has.