The first one is the answer
isotopes of an atom have different number of neutrons . the number of protons are not different in isotopes of an atom
The answer is the last option. Electronegativity is the measure of the attraction that an atom has for electrons involved in chemical bonds. It relates to covalent bonds where electrons are shared. The Pauling scale is the most used.
<span>Fe(NO3)2
The NO3 part is a poly-atomic ion with total charge -1.
This is because Fe has a +2 charge and two NO3's with a -1 charge will balance out to 0.
Most often we just make the assumption that Oxygen has a -2 oxidation number because it is very electro-negative.
So to find N, we just need an oxidation number that balances out with 3(-2) to get -1 (the total charge of the ion)</span>
