The mass of N2F4 produced by the reaction of 2.0 g of NH3 and 80 g of F2 is 3.56 g. What is the percent yield?
2NH3 + 5F2 > N2F4 + 6HF
(a) 79.0
(b) 71.2
(c) 84.6
(d) None of these​