题目

点燃黑火药在发生爆炸时发生如下反应2KNO3+3C+S===K2S+N2 ↑+3CO2↑，下列说法正确的是A. KNO3是氧化剂，C 和S是还原剂B. 产生22.4L气体，转移电子的物质的量为3molC. N2和CO2都是氧化产物D. 单质碳发生氧化反应 答案：【答案】D【解析】A、反应中N元素化合价从+5价降低到0价，得到5个电子，S元素化合价从0价降低到－2价，得到2个电子，碳元素化合价从0价升高到+4价，失去4个电子，所以KNO3和S是氧化剂，C是还原剂，A错误；B、产生的22.4L气体不一定处于标准状况下，不能计算转移电子的物质的量，B错误；C、根据以上C根据短文内容及首字母提示，填写所缺单词，使短文意思完整，每空限一词。(25分)   It seems to us that the earth stands quite stilK 静止的) . But it is really m l all the time. It turns around a makebelieve (虚幻的) line t 2 its center. We call this make-believe line the earth’s axis (地轴) . The two e 3 of the earth’s axis are called its poles (极) . The earth travels twentyfour hours around its axis o 4 .   We look at the sun and say it “travels” a 5 the sky,but the sun doesn’t really do s 6  . The turning of the earth makes us f 7 as if the sun were moving across the sky. We can’t see that the earth is moving because everything e 8 on the earth is turning with us. As the earth turns around every twentyfour hours,first one half f 9 the sun and then the other half. When our half of the earth is facing the sun,we say it is “day”. When our half is a 10 from the sun,we say it is “night”. It is the turning of the earth that tells us when to go to bed and when to get up.1.m 2. t 3. e 4. o 5. a6.s 7. f 8. e 9. f 10. a