Calculate the percentage by mass of oxygen in (nh4)2co3

Modern weaponry has increased the number of deaths in wars and violent conflicts.

What are the first two quantum numbers for the electrons located in subshell 4d? what are the first three quantum numbers for the electrons located in subshell 2s? how many electrons can be held in a sublevel l = 3? how many electrons can be held in the energy level n = 4? how many electrons in an atom can share the quantum numbers n = 4 and l = 3?

What is the molar mass of the anhydrous compound? answer using four significant figures. 36.02 g/mol 120.15 g/mol 156.12 g/mol