<span>N2 - Element; Pure substance O2 - Element; Pure substance N2O - Compound; Pure Substance Air - Homogeneous; Solution</span>
I think D?? I apologize if not-check in other answers to be sure ^^
The reactants, products, coefficients, subscripts. ( I forgot the rest lol)
n = m/M = 2/18 = 1/9 ~0,1 mol
D. As more electrons are added to an element, the number of electron orbitals being filled increases
