Because in CH4 the valence electrons of Carbon are being pulled away from the nucleus with the same force (since all hydrogen has the same electronegativity).So charges are equally distributed throughout the atom and the atom is non-polar. In CH3Cl Cl has a different electronegativity than H, so charges aren't equally distributed and therefore the molecule is polar.
        
                    
             
        
        
        
Answer:
The nucleus of an atom consists of Protons and Neutrons.-A.
 
        
                    
             
        
        
        
0.53313648 feet = 16.25cm
        
             
        
        
        
Answer:
Explanation:
In weight/volume (w/v) terms,
    1 ppm = 1g m-3 = 1 mg L-1 = 1 μg mL-1 
200 mL = 0.2 L
15 / 0.2 mg L-1 =75 ppm