Answer:
B. 126
Explanation:
the scale is 1 to 42 so the scale would be:
 3 cm:x cm
3 * 42 = 126 cm
 
        
             
        
        
        
So diffusion is inversely proportional to mass ! 
so as mass of the particle increases, diffusion decreases !
        
             
        
        
        
Answer:
The mass of the nucleus is almost the same as the atom because a majority of the mass of an atom is stored in the nucleus.
The volume of an atom is larger than the nucleus. The nucleus is a tiny, concentrated area inside of the atom. Atoms are mostly empty space inside.
Explanation:
 
        
             
        
        
        
your answer will be : 
B. <u>Na has a lower</u> <u>electronegativity than H</u>
because Na belongs to alkali metals which are least electronegative (most electro positive) but hydrogen is a non metal, it has higher electronegativity as compared to metals like Sodium (Na).