问题 选择题

实验室制取二氧化碳,下列各组药品中最合理的是(  )

A.稀盐酸和碳酸钠

B.稀硫酸和大理石

C.稀盐酸和石灰石

D.木炭燃烧

答案

A、碳酸钠与盐酸反应速率非常的迅速,不容易控制反应速度,所以不适合实验室中制取二氧化碳,故A不合理;

B、大理石和稀硫酸反应能生成微溶物硫酸钙,覆盖在石灰石表面阻止反应进行,故不适合实验室中制取二氧化碳气体,故B不合理;

C、石灰石和稀盐酸反应速率适中,原料易出,价格便宜,所以实验室制取二氧化碳通常选用石灰石和稀盐酸,故C合理;

D、木炭燃烧虽然能够产生二氧化碳,但是难以收集,所以不适合实验室中制取二氧化碳,故D不合理.

故选C.

阅读理解

We often find many people are complaining about their work around us. It’s clear that we can not deal with the pressure caused by work at all. So how can we have a happy working day? __1___

Make yourself energetic every morning. It means you should not stay up too late. You should take a comfortable shower and go to bed before 22:00 every night. __2__

Keep smiling once you open your eyes. When getting up from your bed, you should always keep a smile on your face. __3___ And you can listen to some soft music you like with your headset on the way to yoru company.

___4__ Before you get down to work, you can make a list of the work that you are going to finish today. You will find out what are the most important things to do and what are the less important ones.

Improve your relationships in the office. Make a habit of saying hello actively to your colleagues, as a gesture of friendship. You will be happier if you can get along well with your colleagues and your life will go more smoothly.

___5__ The key is whether you have a possive attitude. The above are my suggestions. Hope they can help you to have a great day!

A.In short, we create real happiness for ourselves.

B.In fact, it’s not so difficult if we can do as follows.

C.List out what you are going to do in the office today.

D.Therefore, we should stop complaining about our work.E. Say hello to your family members and friends on the road.

F. Have the right attitude towards work and the people around us.

G. Plenty of sleep is healthy and it can offer you a whole day’s energy.

不定项选择