设NA表示阿伏伽德罗常数，下列说法正确的是（ ）
A．在25℃、101kPa下，11.2L氧气所含的原子数为NA
B．0.5molNa与足量水发生反应转移的电子数为NA
C．20g重水（D2O）所含的电子数为10NA
D．在标准状况下，5.6L的CCl4中所含的氯原子总数为NA
A、不是标准状况，不能使用气体摩尔体积vm=22.4L/mol，故A错误．
B、Na与水发生反应生成钠离子，一个钠原子失去一个电子生成钠离子，所以转移的电子数与钠原子数相等，为0.5NA，故B错误．
C、n（D2O）=
=m(D2O) M(D2O)
=1mol，20g重水（D2O）所含的电子数为N（电子数）=）=10n（D2O）NA=10NA，故C错误．20g 20g/mol
D、标况下，CCl4是液体，气体摩尔体积vm=22.4L/mol不适用于该物质，所以5.6L的CCl4中所含的氯原子总数不是NA，故D错误．
故选C．
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| Today, English is spoken in many countries. 1 English spoken in the UK is a little different from that in the USA in spelling, meaning, pronunciation, grammar, usage and so on. Sometimes, 2 English spoken in the UK is very different in every region (区域) 3 the country. Differences in spelling don't 4 speakers of British English from understanding the meanings of the words. 5 , they don't prevent speakers of American English from understanding the meanings either. 6 in spelling are not a big problem for even speakers of English as a 7 language. However, when different words in British English and American English are used to 8 the same thing 9 the same word has different meanings in British English and American English, sometimes people will not be understood if they don't know common differences between British English and American English in meanings and usages. Sometimes even Americans and British people do not 10 each other because of different word meanings. 11 , the British word "brolly" is an"umbrella" in America. And the British 12 potato chips "crisps". All of these differences led British writer George Bernard Shaw to 13 that Britain and America are two countries 14 by the same language! That's the reason why confusion or misunderstanding will be caused in some situations. Of course, such confusion will 15 happen to speakers of English as a second language. | ||||
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