题目

多硫化钠Na2Sx在结构上与Na2O2，FeS2等有相似之处，Na2Sx在碱性溶液中可被NaClO氧化成Na2SO4，而NaClO被还原成NaCl，反应中Na2Sx与NaClO的量之比为1：16，则x值是              （    ）              A．5      B．4       C．3       D．2 答案：A 解析: 利用整体法计算。1molNaClO得电子2mol，Na2Sx中Sx2-显示-2价，反应后生成xmol Na2SO4，转移电子6x-（-2）=（6x+2）mol，16×2=6x+2，解得x=5.请阅读下列五则发明的描述，将其与下面的图片相匹配，其中有一项为多余选项。1.It was invented in 1923 by Fred W.Wolf. This is a large piece of electrical（有电的）kitchen equipment（设备）and it is used for keeping food and drinks cold so that they can stay fresh. 【1】2.It is said that it was invented by Lu Ban's wife. She didn't want her husband to get wet in the rain what he worked outside. So she used bamboo and oilpaper to make it. Now it is popular all over the world and it is made stronger and more convenient for people to see. 【2】3.It is traditional musical instrument. You can play it by beating it with sticks（棒子）or with your hands. People in the northwest parts of China often play it together during big festivals or weddings（婚礼）. 【3】4.It is a large square electrical machine which was invented by an American scientist Alva J. Fisher. It can be used for washing and drying dirty clothes. It can help people save a lot of time. 【4】5.it first appeared as big as at house, so it was not convenient for people to use it. But with development of science and technology, we can use it almost everywhere. We can carry it with us and use it to store（储存）or search for information, send emails and play online games. 【5】A. B. C. D. E. F.