Nitrogen gas can be prepared in the laboratory by the reaction of ammonia with copper(II) oxide according to the following unbalanced equation.

NH3(g) + CuO(s) N2(g) + Cu(s) + H2O(g)

If you pass 26.3 g of gaseous NH3 over a bed of solid CuO (in stoichiometric excess), how many grams of N2 can be isolated?

(a) 21.6 g (b) 28.8 g (c) 43.3 g (d) 86.5 g