问题 选择题

下列操作中,完全正确的一组是(  )

①用试管夹夹持试管,试管夹从试管底部上套,夹在试管中上部

②给盛有液体的体积不超过1/3容积的试管加热

③用饱和的Na2CO3溶液除去CO中的CO2

④将试管平放,用纸槽往试管里送人固体粉末后,然后竖立试管

⑤取用放在细口瓶的液体时,取下瓶塞倒立放在桌面上,倾倒液体时瓶上的标签对着地面

⑥将烧瓶放在桌上,用力塞紧塞子

⑦用坩埚钳夹取加热后的蒸发皿

⑧制取Fe(OH)2时将滴管垂直伸进试管内的液体中

⑨稀释浓硫酸时,把水迅速倒入盛有浓硫酸的量筒中

⑩检验装置的气密性时,把导管的一端浸入水中,用手捂住容器的外壁或用酒精灯微热.

A.①②④⑦⑧⑩

B.①④⑤⑦⑨⑩

C.①④⑤⑦⑧⑩

D.①②⑤⑦⑨

答案

①用试管夹夹持试管时,试管夹应从试管底部上套,夹在试管中上部,或离试管口的1/3处,故①正确;

②给试管中的液体加热,为避免液体沸腾时飞溅出来,液体的体积不能超过试管容积的1/3,故②正确;

③用饱和的Na2CO3溶液除去CO中的CO2,利用的是碳酸钠水解显示的碱性吸收二氧化碳,但吸收量少,速率慢,除杂不完全,故③错误;

④粉末状固体放入试管中,先将试管平放,用纸槽往试管里送人固体粉末后,然后竖立试管,避免了故粘在试管内壁,故④正确;

⑤取用放在细口瓶的液体时,取下瓶塞倒立放在桌面上,倾倒液体时瓶上的标签对着地面,会使残留的液体腐蚀标签,应该标签朝着手心,故⑤错误;

⑥将烧瓶放在桌上,用力塞紧塞子,容易把烧杯口弄破,这些玻璃仪器都是很脆弱的,塞塞子要慢慢的旋紧,故⑥错误;

⑦坩埚钳可用于移走正在加热或很热的蒸发皿,是实验基本操作的要求,故⑦正确;

⑧制取Fe(OH)2时将滴管垂直伸进试管内的液体中,为了防止生成的氢氧化亚铁很快被氧化,便于观察白色沉淀的生成,故⑧正确;

⑨稀释浓硫酸时,应把浓硫酸沿烧杯内壁慢慢加入水中,并不断搅拌,因为水的密度比浓硫酸小,把水加入浓硫酸,溶解过程中温度升高容易引起液体飞溅引起安全事故,量筒是量取液体体积的量具,不能用来溶解液体,故⑨错误;

⑩检验装置的气密性时,把导管的一端浸入水中,用手捂住容器的外壁或用酒精灯微热,导气管口处有气泡冒出,松开手,导气管中上升一段水柱,证明气密性完好,故⑩正确;

综上所述①②④⑦⑧⑩正确

故选A.

单项选择题
阅读理解

       Many parents who welcome the idea of turning off the TV and spending more time with the family are still worried that without TV they would be too often on call as entertainers(娱乐者) for their children.They remember thinking up all sorts of things to do when they were children.But their own children seem different, less good at finding things to pass the time, somehow.When there’s nothing to do, these parents notice regretfully that their children seem unable to come up with anything to do besides turning on the TV.

One father, for example, says, “When I was young, we were always thinking up things to do, projects and games.We certainly never complained in an angry way to our parents, ‘I have nothing to do”.He compares this with his own children today: “They are simply lazy.If someone doesn’t play with them, they’ll happily sit there watching TV all day.”

There is one word for this father’s disappointment: unfair.It is as if he were disappointed in them for not reading Greek though they have never studied the language.He feels his children’s lack of inventiveness a great pity, as if the ability to play were something born that his children are missing.In fact, the tendency(倾向) to play is built into the human species, but the actual ability to play—to imagine, to invent in a playful way, and the ability to gain satisfaction after successful effort from it—these are skills that have to be learned and developed.

Such disappointment, however, is not only unjust, it is also destructive(毁灭性的).Sensing their parents’ disappointment, children come to believe that they are, indeed, lacking something, and that this makes them less worthy of admiration and respect.Giving children the chance to develop new things to enjoy themselves, to enrich their knowledge and experience and discover the pleasure of doing things on their own is, on the other hand, a way to help children develop a confident(自信)feeling about themselves as able and interesting people.

小题1:Many people think that, instead of watching a lot of TV, their children should_______.

A.think up things to enjoy themselves

B.find chances to talk with parents

C.enjoy themselves outdoors

D.sit silently studying Greek小题2:Fathers often blame their children for not being able to play by themselves.This is unfair because________.

A.they do not lack the ability to play

B.they have not been given the opportunities to learn and develop their ability

C.the children are too young to do that

D.the children are not really lazy, but there’s nothing for them to do小题3:When parents show continuous disappointment in their children, the children will________.

A.be more disappointed

B.refuse to learn new things

C.discover the pleasures of doing things on their own

D.lose their confidence and respectability小题4:What is the author’s main idea?

A.Parents should give children more help on how to be inventive.

B.Turning off the TV will help us solve a lot of family problems.

C.It’s not right for parents and children to blame(抱怨) each other.

D.Today’s children are becoming less able and independent than before.