The events of inspiration begins with the; 
Impulses are conducted on the phrenic nerve to muscle fibers in the diaphragm contracting them.
As the dome shaped diaphragm moves downward the thoracic cavity expands.
At the same time the external intercostal muscles may contract raising the ribs and expanding the thoracic cavity further.
The intra-alveolar pressure decreases 
Atmospheric pressure greater than intra-alveolar pressure forces the air into the respiratory tract through the air passages.
The lungs fill with air.
        
             
        
        
        
Hydrogen because it only has one valence electron I believe.
        
             
        
        
        
Answer:
Population 
Explanation:
population is a group of organisms of the same species who inhabit the same particular geographical area 
 
        
             
        
        
        
A. behavioral isolation is when the plant or animal acts a particular way to attract their counterparts, like mating rituals.
geographic isolation is the natural barrier preventing similar species from interacting. for example, Galapagos Islands are the only home of flightless cormorants because the islands are so far from any other land for them to invade.
Temporal isolation is when two of the same or similar species cannot reproduce as a result of mismatched sexual maturity.
B. the isolation of two frog species by mating call is behavioral isolation.
        
             
        
        
        
This question is pretty vague and confusing.