Answer:
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Explanation:
 
        
             
        
        
        
Answer:D. Ratio of oxygen/nitrogen 
Explanation: the ratio will never change no matter the air pressure!
 
        
             
        
        
        
Answer:
Hydrogen chloride (HCl), a compound of the elements hydrogen and chlorine, a gas at room temperature and pressure. A solution of the gas in water is called hydrochloric acid.
Explanation:
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Answer: 
Alkali metals are soft and have low melting points.
 
        
             
        
        
        
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