This is given by Avogagro number: 1 mol = 6.02*10^23 particles
Then you can do whichever to these two relations, because they are equivalent:
- 1mol / 6.02*10^23 representative particles, and
- 6.02*10^23 representative particle /1 mol
Only the second option of the question includes one of the valid conversion factors. Then, the conversion factor of the second option is the right answer
It would be a positive charge because it lost two electrons, if the charge was neutral it would be the same amount of protons and electrons, if the charge was negative the electrons would be 20 instead of 18. So in this case it is positive.
