题目

1g H2燃烧生成液态水放出142.9kJ的热量，下列热化学方程式正确的是A．2H2(g)+ O 2(g) = 2H2O(1)                         H = —142.9kJ·molˉlB．2H2(g)+ O 2(g) = 2H2O(1)                          H = —571.6kJ·molˉlC．2H2+O2 = 2H2O                                 H = —571.6lkJ·molˉlD．H2(g)+O 2(g) = H2O(1)                          H = +285.8kJ·molˉl We were swimming in the lake ______ suddenly the storm started.A. until B. while C. when D. before