题目

一定量的Fe、FeO、Fe2O3、Fe3O4的混合物中加入350 mL 2 mol·L－1的稀硝酸恰好使混合物完全溶解，放出2.24 L NO(标准状况)，往所得溶液中加入KSCN溶液，无红色出现。若用足量的H2在加热条件下还原相同质量的混合物，所得到的铁的物质的量为(   )    A．0.21 mol     B．0.25 mol           C．0.3 mol          D．0.35 mol阅读理解 阅读下面短文，从每题所给的四个选项中，选出最佳选项。 　　The idea of light pollution has developed with the increase of lights in cities. In many areas, this light makes it difficult or impossible to observe stars and planets in the night sky. 　　There are a number of reasons why light pollution is important. One has become clear at the Mount Wilson Observatory(天文台) near Los Angeles, California. Today, light from Los Angeles makes the night sky above Mount Wilson very bright. It is no longer an important research center because of light pollution. 　　Light pollution threatens(威胁) to reduce the scientific value of research telescopes in other important ob servatories. They include Lick Observatory near San Jose, California and Yerkes Observatory near Chicago, Illinois. 　　Light pollution is the result of wasted energy. Bright light that shines into the sky is not being used to provide light where it is needed on Earth. Poorly designed lighting causes a great deal of light pollution. Lights that are brighter than necessary also cause light pollution. 　　Recently, two Italian astronomers(天文学家) and an American environmental scientist created a world map of the night sky. The map shows that North America, Western Europe and Japan have the greatest amount of light pollution. 　　Most people in America are surprised to find out that they are able to see our own galaxy(星系), the Milky Way(银河系), with their own eyes. But about three-fourth of Americans cannot see the Millky Way because of man-made light. 　　Objects in the night sky are resources that provide everyone with wonder. But light pollution threatens to prevent those wonderful sights from being seen. 1．Light pollution usually occurs ________. [　　] A．in cities B．in the country C．in wild areas D．in developing countries 2．People can not see the stars in the sky because of ________. [　　] A．air pollutionB．water pollution C．light pollutionD．gas pollution 3．The victim(受害者) affected by the light pollution is ________. [　　] A．childrenB．grown-ups C．studentsD．observatories 4．There is less light pollution in ________. [　　] A．the United StatesB．Canada C．FranceD．Egypt