【多选题】某短周期元素原子的最外电子层只有2个电子,该元素可能是 [ ]
【简答题】A、B、C、D均是短周期元素,A和B同周期, B和C同族,A元素族序数是周期数的三倍,B原子最外层电子数是内层电子数的二倍,B与A能生成化合物BA 2 ,C与A生成化合物CA 2 , A的阴离子与D的阳离子电子层结构相同,都与氖原子的电子层结构相同,D 的单质与A 的单质在不同条件下反应,可生成D 2 A或D 2 A 2 。请回答 (1)写出元素符号A: ,B: ,C: 。 (2)D 2 A的电子...
【简答题】阅读文章,回答题: Chengdu has dozens of new millionaires, Asia’s biggest building, and fancy new hotels. But for tourists like me, pandas are its top____61__________(attract). So it was a great honour to be i...
【单选题】三种短周期元素A、B和C,它们的原子序数是依次增大,其中C的原子半径在短周期的主族元素中最大,B和C的最外层电子数之和等于A的最外层电子数的2倍,且A是构成有机物的重要元素,下列说法正确的是( )
C.
C离子具有很强的还原性,B离子具有很强的氧化性
【单选题】对齿轮传动的凸轮轴传动机构,下列齿轮的磨损对定时的影响最大的是()。
【简答题】阅读下面材料,在空白处填入适当的内容(1个单词)或括号内单词的正确形式。 Chengdu has dozens of new millionaires,Asia’s biggest building, and fancy new hotels. But for tourists like me, pandasare its top____61_(attract). So it was a grea...
【简答题】Chengdu has dozens of new millionaires, Asia's biggest building, and ________(奇特的)new hotels.
【简答题】Teahouses in Chengdu There is a saying, “China has the best teahouses in the world and Chengdu has the best teahouses in China.”Chengdu has not only many teahouses but also the special ways of serving...
【单选题】马蒂斯的艺术中借鉴了( )的成就,他作品中的装饰风格图案的处理都与此有关。
【判断题】由于欠烧f-CaO结构疏松多孔,所以对水泥安定性影响不大。