问题 问答题

(12分)D、A、B、C为四种原子序数依次增大的短周期元素,A、B、C同周期,A的原子半径是同周期中最大的;B、D同主族。已知D元素的一种单质是日常生活中饮水机常用的消毒剂,C元素的单质可以从A、B两元素组成的化合物的水溶液中置换出B元素的单质。

(1)C元素在周期表中的位置     周期        族。

(2)A、B元素形成的常见化合物水溶液显        性,原因是(用离子方程式表示)                用石墨做电极电解该化合物的水溶液,则阴极反应式为                       

(3)A、D元素可以形成化合物A2D2,写出A2D2与CO2反应的化学方程式                  (用元素符号表示)。该反应中还原剂是        

(4)B元素的单质在不同的条件下可以与O2发生一系列反应:① B(s)+O2(g)=BO2(g);△H=-296.8kJ/mol②2BO2(g)+O2(g) 2BO3(g);△H=-196.6kJ/mol

则1 mol BO3(g)若完全分解成B(s),反应过程中的热效应为             

答案

(1)第三周期第ⅦA族;            (2)碱性;S2-+H2OHS-+OH-2H++2e-=H2↑;

(3) 2Na2O2+2CO2 =Na2CO3+ O; Na2O2;  (4)吸收395.1KJ的热量(或+395.1KJ)

题目分析:根据题意可知这几种元素分别是:A是Na;B是S;C是Cl;D是O。(1)Cl元素在周期表中的位置是位于第三周期第ⅦA族;(2)A、B元素形成的常见化合物Na2S是强碱弱酸盐,弱酸根离子水解使水溶液显碱性。水解的两种方程式为:S2-+H2OHS-+OH-;用石墨做电极电解该化合物的水溶液,由于放电能力H+>Na+,所以在阴极是H+得到电子。该电极的反应式为2H++2e-=H2↑;(3)Na2O2与CO2反应的化学方程式是2Na2O2+2CO2 =Na2CO3+ O;在该反应中氧化剂、还原剂都是Na2O2。①×2+②足量可得BO3(g)="3/2" O2(g)+ B(s) ΔH=+395.1KJ/mol.

阅读理解

Life in the twenty-first century will be very different from life today. Between then and now many changes will take place, but what will the changes be?

The population is growing fast. There will be many people in the world and most of them will live longer than people live now.

Computers will be much smaller and more useful, and there will be at least one in every home. And computer studies will be one of the important subjects in schools then.

People will work fewer hours than they do now and they will have more free time for sports, watching TV and travelling. Travelling will be much easier and cheaper. And many more people will go to other countries for holidays.

There will be changes in our food, too. Maybe no one will eat meat every day, instead they eat more fruit and vegetables. Maybe people will be healthier.

Work in the future will be different, too. Dangerous and hard work can be done by robots. Because of this, many people will not have enough work to do. This will be a problem.

小题1:There will be _________ in the future.

A.small population

B.few changes

C.more people

D.few people小题2:In the future the computer will be _________.

A.much bigger and few people will use it

B.much smaller and more useful

C.smaller and not many people will use it

D.bigger and a lot of people will use it小题3:In the future more people _________.

A.will go to other countries for holidays

B.will study at school

C.will go earlier

D.will work for many hours小题4:People will prefer _________ to _________ in the future.

A.meat and vegetables; fruit

B.meat; fruit and vegetables

C.fruit and meat; vegetables

D.fruit and vegetables; meat小题5:The robots will _________ in the future.

A.do the dangerous work

B.do all the work

C.do only housework

D.do the easy work for people

单项选择题