将铁片加到2L0.5mol/LFeCl 3溶液中，当Fe 3+和Fe 2+的浓度相等时，铁片的质量减少了（  ）

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku_ where sourceid='19804' and id < 1718684 and id<>'1718684' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='19804' and id > 1718684 and id<>'1718684' order by id asc limit 5