题目

Bob always took the newspaper to Grandpa White's home before going home. Grandpa White's was at the end of the road. Bob liked Grandpa White. He was often waiting for him near the front gate with sweets or a nice cake. Besides, He often asked Bob about things he was doing, what he was going to do for the summer and what he liked to do. The thing that Bob didn't like about Grandpa was his never-ending stories about his boyhood(童年)in California. Bob was never asked to hear about Grandpa's boyhood, but he couldn't get away. After Grandpa's wife died in October, Bob could see that Grandpa 实验室利用H2+CuOCu+H2O反应原理(实验装置见下图),测定水分子中氢氧原子的“相对原子质量”比值,实验室中制得的氢气中有少量水蒸气。则有关实验操作说法正确的是 A.只需要获得氧化铜粉前后的质量差 B.只需要获得无水硫酸铜前后的质量差 C.若没有“甲”装置,所得比值偏大 D.实验中一定要通入足量的氢气将氧化铜完全反应
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