下列鉴别物质的方法中，不切实可行的是
A．用稀硫酸区分黄铜(Cu、Zn)和黄金
B．用水鉴别氢氧化钠固体和碳酸钙固体
C．用碳酸钠溶液鉴别氢氧化钙溶液和氯化钙溶液
D．用尝区分厨房里的面粉和白糖
答案：C
题目分析：A、根据金属的活动性，锌会与稀硫酸反应，而金不会，所以可用稀硫酸区分黄铜(Cu、Zn)和黄金，正确， B、氢氧化钠固体易溶于水且同时放出大量的热，而碳酸钙固体不溶于水，所以可用水鉴别氢氧化钠固体和碳酸钙固体，正确，C、氢氧化钙溶液和氯化钙溶液都能与碳酸钠溶液反应生成白色沉淀碳酸钙，，所以无法鉴别，错误，D、白糖有甜味，而面粉没有，所以可用尝区分厨房里的面粉和白糖，正确，故选C
| 阅读短文，掌握其大意,然后从A、B、C三个选项中,选出一个最佳选项。 | |||
| One day when Jamie came home after school, his mother had worry on her face. He knew she was thinking of _1_. "It's bad out there. Black clouds are coming from the sea." Jamie said. "Yes, I'm thinking of those fishing boats at sea." She said. At that moment, _2_ went out. Jamie and his mother were in the dark. "The coast line (海岸线) will be in the dark." Jamie's mother said. She got more _3_. "Questions always come in threes. I broke my best glasses this morning, and my sister had cold." "Now, don't worry, mum. They're _4_ to come through this at night." But Jamie really worried about those fishing boats himself. The fishing boats would _5_ the cove (海湾) in the dark. Jamie took flares (火焰信号弹) and rushed into the wind. There was a cliff by the sea. He started to climb. He _6_ himself up hand over hand. At last he reached the top. He _7_ three times. On the fourth try he fried out one of the flares. It rosined cut into the black sky in bright light. Then he saw an answering flare up at sea. Jamie fired off two more. He saw another answering flare up, then another, then another. The answering flares from the fishing boats showed them _8_ the entrance to the cove but then changed course and were _9 sailing into the co  ve. They were almost home.Jamie helped _10_ the fish men of the village. | |||
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