What is the maximum amount of moles of NaCl that will dissolve in 1000ml of solution?
Given: 181 sodium ions and 181 chloride ions have dissolved in 5.00 x 10^-23 liters of water

Yes she is correct. the answer is completely correct

And a) oxygen i believe

Well you can immediately rule out a and d because if a metal were to lose or gain protons, then it would become a different element all together. the answer here is b because the positive symbol with a number refers to how many electrons the metal can give away to become stable.