Buhrs atomic model differed from ruthofords because it explained that electrons exist in specified energy levels surrounding the nucleus. This means that, Ruthoford believed that electrons can't do very much. However, Buhrs' model showed that electrons are much more powerful than anyone else believes they can be.
Check the 1st 2nd 3rd and 4th boxes
Same magnitude (1000N) and opposite direction
you may also answer -1000 N
So the question ask to formulate an expression to represent the amount of air required to inflate the balloon from a radius of R+4 and the expression would be V=16pi/3*(3r^2+12r+16). I hope you are satisfied with my answer and feel free to ask for more if you have question and further clarifications