Directions:Question 20 and 2l refer to the following experim

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Directions:Question 20 and 2l refer to the following experiment:
Three different pairs of metal wires are placed separately in petri dishes (as shown in
the diagram below) containing a mixture of gelatin,rust indicator and
phenolphthalein solution.
第一个碟子是Fe 和Mg
第二个是Fe和Cu
第三个是Fe和Fe
21.In Dish II,which of the following colours will develop around the iron wire and the copper
wire?
iron wire copper wire
A.pink blue
B.blue pink
C.pink no colour
D.blue no colour

ust indicator,是铁锈指示剂,会与溶液中的Fe2+反应呈蓝色,所以铁丝上是蓝色
由于电子转移,在铜丝附近会生成OH-,遇酚酞呈粉色
所以选A

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