问题 填空题

综合利用海水可以制备食盐、纯碱、金属镁等物质,其流程如下图所示:

(1)反应①~⑤中,属于氧化还原反应的是   (填编号)。

(2)写出反应②的离子方程式   

(3)X溶液中的主要阳离子是Na+   

(4)粗盐中含有Na2SO4、MgCl2、CaCl2等可溶性杂质,为制得纯净的NaCl晶体,操作如下:

①溶解;②依次加入过量的BaCl2溶液、NaOH溶液、Na2CO3溶液;③  ;④加适量盐酸;⑤    。(请补全缺少的实验步骤)

(5)检验纯碱样品中是否含NaCl应选用的试剂是        

答案

(1)⑤ (2分) 

(2)Mg (OH)2+2H+ = Mg2+ + H2O (2分)

(3)NH4+(2分)

(4)过滤 (2分) 、蒸发结晶(其它答案合理也给分)(2分)   

(5)稀硝酸、AgNO3溶液(2分)

题目分析:(1)反应①②属于复分解反应,③属于化合反应,④属于分解反应,⑤为氧化还原反应;(2)酸碱中和反应,Mg (OH)2不溶于水写成化学式,Mg (OH)2+2H+ = Mg2+ + H2O;(3)该反应为氨水、二氧化碳、氯化钠反应生成碳酸氢钠沉淀和氯化铵,X溶液中的主要阳离子是NH4+和Na+;(4)加入盐酸前生成的沉淀能溶解于盐酸,故应过滤除去沉淀后再加盐酸,然后通过蒸发结晶得到氯化钠晶体;(5)检验样品中是否含有氯离子,用硝酸酸化的硝酸银。

阅读理解
Stress (压力) is everywhere in our everyday life. Not only men have it, but also women and young people.
The most important reasons of stress are:death, diseases, exams, making money, getting married, moving houses, changing jobs, ending friendships and so on .
How do you know whether you have stress? Could you give your answers to the following questions?
 
Yes
No
Do you easily get angry?
 
 
Do you often sleep badly?
 
 
Do you get headaches a lot?
 
 
Do you take sleeping pills?
 
 
Do you find it difficult to relax?
 
 
Do you usually hide your feelings?
 
 
Do you smoke and drink a lot to keep quiet?
 
 
Do you find it difficult to put your heart into something?
 
 
If you answer “Yes” to more than two of these questions, you are one of those people with stress. So what can you do about it?
Doing relaxing exercises, talking with friends and listening to light music are all usual ways of relieving(减轻) stress. However, doctors now say that there are easier ways—people should laugh and smile more often. When you laugh and smile, your body relaxes. They also say that people, especially men, should cry more often, be­cause crying is the natural way of relieving stress.
小题1:Who has got stress in everyday life?
A. Men and women.          B. Young people.        C. Both A and B.
小题2: If you have over            problems listed in the table, you are the person with stress.
A. two  B. three                    C. eight
小题3:Which of the followings is NOT the reason of stress?
A.Taking exams. B. Taking sleeping pills.   C. Making money.
小题4:What’s the easier way to relax your body?
A. Talking with friends.       B Doing relaxing exercises.  
C. Laughing, smiling and crying.
小题5:The main idea of the passage is           .
A.about stress and how to relieve your stress
B. that there are many reasons for having stress
C.that laughing and smiling more can help relieve your stress
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