An amount of green crystal is dissolved in water to give a 25.00mL solution. This is then titrated with 0.0125 M KMnO4. The buret reads 0.15 mL at the beginning of the titration and 27.95 mL at the end of the titration. What is the number of moles of C2O4^-2 ion in the sample?

A.(nh4)(2co3)is the correct answer 

D. h2o + h2o > h3o + oh- confirmed.

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.

Number of molecules=(12.01+2x15.9994)/112 x na