单项选择题
A.0.31 B.0.40 C.0.50 D.0.60
A.2.128kJ/mol B.49.02kJ/mol C.9.242kJ/mol D.10.33kJ/mol
A.38.83kJ/mol B.50.81kJ/mol C.-38.83kJ/mol D.-50.81kJ/mol