试题与答案

将铁丝放入少量稀硫酸中,能观察到的现象有:铁丝表面______;溶液由_____

题型:填空题

题目:

将铁丝放入少量稀硫酸中,能观察到的现象有:铁丝表面______;溶液由______色变成______色.将光亮的铁钉放入硫酸铜溶液中,能观察到的现象有:铁钉表面由______色变为______色;溶液由______色逐渐变为______色.

答案:

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(1)(2)(3)周期性变化 元素的周期数即为原子的核外电子层数;元素的主族序数即为原子的最外层电子数(1)根据元素周期表的结构,元素周期表有七个横行,即七周期;有18个纵行,其中有七主族、七副族、第Ⅷ族...

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题型:单项选择题

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第(2)空应选择()

A.because

B.though

C.until

D.while

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