I'm pretty sure its B or C. Sorry, hope this helped some....??
Because percent relates to mass not molecules. Carbon has a mass of approximately 12 and oxygen has a mass of approximately 16. Since they don't have equal masses, one would have a greater percentage
The two nitrogen atoms are in different oxidation states. The one in the
ammonium ion (NH4+) is in the 3- oxidation state while the one in the
nitrate ion (NO3-) is in the 5+ oxidation state.