Sound waves are waves of growing larger and smaller, making it seem elastic through substances, such as air.
        
             
        
        
        
Micrometer and millimeter
        
             
        
        
        
 An ecosystem is a geographic area where plants, animals, and other organisms, as well as weather and landscape, work together to form a bubble of life. Ecosystems contain biotic or living, parts, as well as abiotic factors, or nonliving parts. Biotic factors include plants, animals, and other organism .  
 
        
             
        
        
        
The CH4 molecule has the lowest molecular weight, so it has the lowest boiling point.
Hope I helped :)
        
             
        
        
        
When two atoms are bonded together, the atom that is LEAST likely to attract electrons to itself is
the atom with the smallest electronegativity