题目

阅读理解 Floods are second only to fire as the most common of all natural disasters.They occur almost everywhere in the world,resulting in widespread damage and even death.Consequently,scientists have long tried to perfect their ability to predict floods.So far,the best that scientists can do is to recognize the potential for flooding in certain conditions. There are a number of conditions,from deep snow on the ground to human error,which cause flooding. When deep snow melts it creates a large amount of water.Although deep snow alone rarely causes floods,when it occurs together with heavy 用铝箔包装0.1 mol金属钠，用针扎出一些小孔，放入水中，完全反应后，用排水集气法收集产生的气体，则收集到的气体为(标准状况) (    ) A.O2和H2的混合气体                           B.1.12 L H2C.大于1.12 L H2                                D.小于1.12 L气体