21) How many moles of phosphine (PH3 ) are produced for every 4.0 moles of hydrogen that react according to the chemical equation below? (molar masses (g/mol): P = 30.97, H = 1.0) 3H2 P2 → 2PH3 A) 1.7 moles B) 4.7 moles C) 3.7 moles D) 2.7 moles E) None of the above