实验中需要1mol•L-1的Na2CO3溶液950mL，配制时应选用容量瓶的规格和称取的Na2CO3•10H2O的质量分别为（ ）
A．950mL，100.7g
B．1000mL，286g
C．500mL，286g
D．1000mL，212g
因需1mol•L-1的Na2CO3溶液950mL，则选择1000mL容量瓶，1000mL=1L；Na2CO3的物质的量为n=1L×1mol•L-1=1mol，
根据碳原子守恒知，碳酸钠的物质的量与Na2CO3.10H2O的物质的量相等，都是1mol；
Na2CO3.10H2O质量为1mol×286g/mol=286g，
即需要1000mL容量瓶、286gNa2CO3•10H2O，
故选B．
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| Miyazaki Umi lives in Odawara, Japan. The 15-year-old girl has learned a lot about China from her father and her school. She likes Chinese culture very much. She has a dream. She hopes one day she can work in China. Different to Umi, Miyata Natsuiyuki's knowledge of China all comes from a book, Romance of the Three Kingdoms. The novel is well known in Japan. In this 15-year-old boy's mind, Chinese people are like the heroes in the book - they work hard for their dreams. Last week, the two finally got a chance to see China. 2008 is the China-Japan Friendly Exchange Year. Invited by the Suzhou People's Association for Friendship, organized by Japan's Children and Life Culture Association, Umi and Natsuiyuki, together with another 63 Japanese people, made a trip to China. They first went to Shanghai. Then, in Suzhou, they saw Kunqu Opera at the Suzhou Art School. Umi and Natsuiyuki said they have found out something new about the country. In Shanghai, the high buildings amazed Umi. "It seems as if all the tall buildings in Japan are here in Shanghai," she said. Natsuiyuki saw bicycles everywhere in Chinese cities."You don't see that in Japan. I think it's good for the environment to ride bikes." Both the boy and the girl think that people in China are very kind and warm-hearted. "Though we only speak broken Chinese and English, they always answered my questions patiently," said Umi. "If you have any difficulties, they come and help you at once," said Natsuiyuki." Even though you cannot speak the language, you forget you are in a foreign country." | |||||||||
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