问题 选择题

实现下列转化,必须加入氧化剂或还原剂的是(    ) 

A.Cl2→HClO+HCl

B.NH4+→NH3

C.NH3→NO

D.P2O5→H3PO4

答案

答案:C

题目分析:氯气溶于水即可生成次氯酸和盐酸,该反应中氯气既是氧化剂,也是还原剂;B中不是氧化还原反应;C中氮元素的化合价升高,需要加入氧化剂;D中P元素的化合价不变,不是氧化还原反应,溶于水即可生成磷酸,答案选D。

点评:该题是高考中的常见题型,属于中等难度的试题,试题侧重考查学生分析问题、解决问题的能力。解答该题需要注意的是一些歧化反应,例如选项A。

单项选择题
单项选择题

A

Ask Dr Jeffers.

This month Dr. Jeffers is answering questions about human brain and how it works. Dear Dr. Jeffers,

One of my colleagues, Felix Moeller, told me that scientists are learning to use computer to ’read minds’. Is there any truth to this story

--Jane Leon, New York, USA

Dear Ms. Leon,

Well, a lot of research is being conducted in this area, but so far, the brain scanning equipment and corresponding computer programs haven’ t been able to actually read thoughts. In one experiment, test subjects(受试者) were connected to scanning equipment and shown two numbers on a screen. They were then asked to choose between adding or subtracting(减)the two numbers. Using this method, researchers were able to follow brain processes and make the correct assumptions (假 设) 70 percent of the time. It’ s not quite mind reading, but it’ s certainly a first step.

--Dr. J.

Dear Dr. Jeffers,

My three-year-old son loves it when I dig my fingers into his sides and tickle (胳肢)him until he laughs uncontrollably. The other day I noticed him trying to tickle himself but he couldn’t do it. Why not

--Glenn Lewis, Vancouver, Canada

Dear Mr. Lewis,

It’s because of how the brain works. The brain is trained to know what to pay attention to and what to ignore. It causes us to ignore physical feelings we expect to happen, but it causes a mild panic reaction when there is an unexpected feeling. For example, you don’ t notice how your shoulder feels while you’ re walking down the street. But if someone comes up behind you and touches you lightly on the shoulder, you may jump in fear. It’ s that unexpected part that causes the tickle reaction.

--Dr. J.

Who has got a little child according to the text().

A. Ms. Leon.

B. Mr. Lewis.

C. Mr. Moeller.

D. Dr. Jeffers.