N₂H₄是一种高效清洁的火箭燃料。0.25 mol N₂H₄（g）完全燃烧生成氮气和气态水时，放出133.5 kJ热量。则下列热化学方程中正确的是
　 

A．1/2 N2H4(g)+ 1/2 O2(g)＝ 1/2 N2(g)+ H2O(l)△H=+257kJ·mol^－^1

B．N2H4(g)+O2(g)＝N2(g)+2H2O(l)△H＝－133.5kJ·mol^－^1

C．N2H4(g)+O2(g)＝N2(g)+2H2O(g)△H＝+534kJ·mol^－^1

D．N2H4(g)+O2(g)＝N2(g)+2H2O(g)△H＝－534kJ·mol^－^1