问题 问答题

我们学习过常见气体的实验室制法,知道了制取气体的一般思路和方法.

(1)实验室制取气体时,确定发生装置需要考虑的两种因素有______(填序号).

A.反应物的状态       B.气体的密度

C.反应的条件         D.气体的溶解性

(2)某实验室的仪器柜里有如下仪器:

仪器①的名称是______.实验室用大理石和稀盐酸制备并收集二氧化碳时,不可能选择的仪器是______(填序号).

(3)老师提出用碳酸钠粉末与稀盐酸制取二氧化碳,其反应的化学方程式为______.为了完成该实验,有四位同学组装了以下发生装置,你认为最合适的一套装置是______(填序号),该装置的最大优点是______.

答案

(1)实验室制取气体时,确定发生装置需要考虑的两种因素有反应物的状态和反应的条件;

(2)仪器①的名称是长颈漏斗;实验室用大理石和稀盐酸制备并收集二氧化碳时,属于固体和液体混合不需要加热的反应,所以不需要酒精灯,二氧化碳能溶于水,所以不能用排水法收集,所以也不用⑤;

(3)碳酸钠粉末与稀盐酸反应生成氯化钠、水和二氧化碳,反应的化学方程式为Na2CO3+2HCl=2NaCl+H2O+CO2↑;该反应是固体和液体混合不需要加热的反应,所以最合适的一套装置是D,该装置的最大优点是能控制反应速率.

故答案为:(1)AC;

(2)长颈漏斗;②⑤;

(3)Na2CO3+2HCl=2NaCl+H2O+CO2↑; D;能控制反应速率.

单项选择题
阅读理解

阅读理解。

     Outside our hotel in Ho Chi Minh City, Vietnam, a seemingly ancient woman waited beside

the door with her hand outstretched. Every day I put my hand in hers as our eyes met. She never

failed to return my smile, my grasp, and my greeting.

    On the last day of our visit, I found myself alone on a busy corner across the street from our

hotel. Bicycles and motorbikes rushed in front of me. As I hesitated on the sidewalk, I felt a hand

on my elbow and looked down to see the smile of my small beggar friend looking up at me. She

nodded her head toward the street, indicating that she would take me across. Together, we moved

slowly into the chaos.

    Then we moved on toward the sidewalk, where she pulled my face down to hers, kissed me on

both cheeks, and then left, still smiling and waving back to me.

Traveling in poorer nations, I have witnessed a variety of ways to deal with beggars. The most

common response of tourists faced with the poverty-stricken is to ignore them and focus their eyes

elsewhere. I have seen people push away an outstretched hand in angry annoyance. A few may drop

a few coins into the hand in a hurry, hoping that other ragged pursuers won't immediately appear on

the scene.

For many reasons, giving money is not the best response to an outstretched hand. Many world

travelers have discovered that the greatest gift they can give is their time and respect. Everyone needs

recognition, to be seen as worthy of being known, to feel appreciated and loved. And I believe that

everyone is worthy and worth knowing.

1. The woman beggars helped the author go across the busy street because __________.

A. the author gave her material assistance  

B. the author treated her kindly and friendly

C. the author would help her as a reward  

D. the author was a foreigner

2. From the story, what position of the beggars in the author's mind might be?

A. equal    

B. superior      

C. lower    

D. valuable

3. In common cases, people will do the following things to the beggars EXCEPT for ________.

A. pretending to see nothing            

B. handing out some money

C. refusing them angrily               

D. greeting them normally

4. According to the author, the most important things beggars really need are _________.

A. mercy and pity

B. money and food  

C. smile and greeting  

D. attention and respect

5. The purpose of the passage is to _________.

A. show how poor the beggars are in Vietnam

B. offer some advice on dealing with begging

C. express what we should offer the beggars

D. describe an experience with a beggar