Can someone describe the Isotopes and compare the difference between the elements

It will fall off and tip over. 

B"hf and f-"  is the correct answer took the test on edgenuity and got it right     

(no3)⁻n has oxidation number x,o has oxidation number -2.(x*1 -2*3) charge of the nitrate ion, and we know that charge of the nitrate ion =-1.so,(x*1 -2*3) =-1x-6=-1x=+5answer a. +5.