搜题请搜索小程序“爱下问搜题”
问题 填空题

写出两个制取氧气以及氧气和硫，铁的反应的文字文字表达式并写出反应类型：

①______，反应类型：______；

②______，反应类型：______；

③______，反应类型：______；

④______，反应类型：______．

答案

①在实验室制取氧气的可以选用高锰酸钾来制取氧气：高锰酸钾

加热
锰酸钾+氧气+二氧化锰，该反应属于分解反应；

②在实验室中制取氧气也可以用过氧化氢溶液来制取氧气：过氧化氢

MnO2
水+氧气，该反应属于分解反应；

③硫和氧气反应生成了二氧化硫，该反应属于化合反应；

④铁和氧气反应生成了四氧化三铁，该反应属于化合反应．

故答案为：①高锰酸钾

加热
锰酸钾+氧气+二氧化锰；分解反应；

②过氧化氢

MnO2
水+氧气；分解反应；

③硫+氧气

点燃
二氧化硫；化合反应；

④铁+氧气

点燃
四氧化三铁；化合反应．

问答题 简答题

试述发电机停役后的三种状态？
查看答案
单项选择题

Magnetic resonance imaging (MRI)—a noninvasive diagnostic procedure—can be used to identify blockages in the coronary arteries. In contrast to angiograms—the invasive procedure customarily used—MRI’s pose no risk to patients. Thus, to guarantee patient safety in the attempt to diagnose arterial blockages, MRI’s should replace angiograms in all attempts at diagnosing coronary blockages.
Which of the following, if true, would most support the recommendation above

A．Angiograms can be used to diagnose conditions other than blockages in arteries.

B．MRI’s were designed primarily in order to diagnose blockages in the coronary arteries.

C．Angiograms reveal more information about the nature of a blockage than an MRI can.

D．An MRI is just as likely as an angiogram to identify an arterial blockage.

E．(E) Some patients for whom an angiogram presents no risk are unwilling to undergo an MRI.
查看答案