搜题请搜索小程序“爱下问搜题”
问题 选择题

下图是空气氧化Fe2+为Fe3+过程中的实验结果，下列有关说法正确的是

[ ]

A．80℃下氧化效果较 50℃好，说明该氧化反应是吸热反应

B．最佳氧化条件为80℃、pH=1.5下氧化4小时左右

C．pH=1.5时氧化效果一定比pH=2.5时好

D．氧化的离子方程式为：Fe2++O2 +4H+=Fe3++2H2O

答案

答案：B

单项选择题

有人研究了汽车速度与每升汽油行驶里程之问的关系，得到相关系数为0.27，但是他们发现速度表出了故障因而不太精确，每小时快了3km，于是对速度表进行了修正，重新求得的相关系数是（）.

A．0.35

B．0.27

C．0.30

D．0
查看答案
判断题

The Customs surveillance zone include following places except ______.
A．Any seaport, railway and high way station, airport, border pass or international postal matter exchange where there is a Customs establishment
B．any place where Customs control is conducted
C．any place without a Customs establishment but which has been approved by the state council as a point of entry and exit
D．any place along the border of the country
查看答案