某实验需要80mL、1mol/L的Na2CO3溶液,现通过如下操作配制: ①称量

题型:问答题

问题:

某实验需要80mL、1mol/L的Na2CO3溶液,现通过如下操作配制:

①称量 g Na2CO3固体放入小烧杯中,加适量蒸馏水溶解.为加快溶解可以使用 玻璃棒搅拌

②待溶液冷却到室温后,小心转入 (填仪器名称)

③继续加蒸馏水至液面至刻度线1~2cm处,改用 (填仪器名称)小心滴加蒸馏水至溶液凹液面最低点与刻度线相切

④将容量瓶塞紧,充分摇匀.

⑤用少量蒸馏水洗涤玻璃棒和烧杯2~3次,每次洗涤的溶液都转入容量瓶,并轻轻摇匀

(1)操作步骤正确的顺序是 (填序号).

(2)使用容量瓶前必须进行的一项操作是 

(3)若所配溶液的密度为1.06g/mL,则该溶液的质量分数为 .

(4)若取出20mL配好Na2CO3的溶液,加蒸馏水稀释成c(Na+)=0.1mol/L的溶液,则稀释后溶液的体积为 mL

(5)在配制Na2CO3溶液时,下列操作中的 会导致结果偏低

①用拖盘天平称量时砝码放在左盘

②将烧杯中的溶液转移到容量瓶时不慎洒到容量瓶外

③定容时俯视刻度线

④未冷却到室温就转移到容量瓶中

⑤干净的容量瓶未经干燥就用于配制溶液.

考点:配制一定物质的量浓度的溶液
题型:问答题

阅读理解。

                                                                           Letter A

Dear Mary,

      I like your programmes very much. I'm now writing to ask you something about American social

customs (社交习惯): My American friend wants me to join them in their dinner party. I am very happy

and have decided to go, but I'm a little worried about it, too. The social customs in my country are very

different from here, so I'm afraid of making mistakes.

     Should I bring a present, such as sweet or flowers? Should I arrive on time or a little late? At the dinner

table, how can I know which fork (叉子) or knife to use? How can I let the family know that I'm thankful

for their kindness

                                                                                                                                Wang Lin

                                                                            Letter B

Dear Wang Lin,

      It's a good idea to bring a small present when you go to a dinner party. Flowers are always nice, or you

may bring a bottle of wine (葡萄酒) if you know that your friends drink it.

     You should arrive on time or five to ten minutes late. Don't get there early. If you're going to be more than

fifteen minutes late, you should call and tell them.

     Try to be free at the dinner table. If you don't know about choosing the right fork or knife, just watch the

other people, and follow them. If you still have no idea of what to do ask the person next to you.

     If you like the food, say so. Of course, you'll thank them for the meal and for their kindness. It's also a

good idea to send a thank-you card the day after.

                                                                                                                                               Mary

1. Mary is possibly _______.

A. a good housewife

B. a TV hostess (主持人)

C. a member of the dinner party

D. a friend of Wang Lin's

2. When you go to a dinner party, you'd better not take _______ with you.

A. some wine

B. some flowers

C. some presents

D. some food

3. If you're asked to a dinner party but not sure about what to bring as a present, it's good to bring _______.

A. some fruits

B. a bottle of wine

C. some flowers

D. a knife and fork

4. Which of the following is NOT proper (适当的) for joining in a dinner party?

A. Get there 15 minutes earlier.

B. Make yourself at home.

C. Follow others to use forks and knives.

D. Thank your friends for the meal.

题型:问答题

事故调查的内容包括事故本身和()两部分。

A.事故车辆

B.道路

C.行人

D.环境

题型:问答题

急性会厌炎()。

A.起病急,有畏寒发热、剧烈的咽喉痛、吞咽困难、讲话语言含糊不清,可有吸气性呼吸困难甚至窒息,很少有声音嘶哑

B.常发生于感冒之后,可有畏寒、发热、乏力等全身症状,局部症状有声音嘶哑、咳嗽、咳痰及喉痛

C.起病较急,主要症状为声音嘶哑、犬吠样咳嗽、吸气性喉喘鸣和吸气性呼吸困难,还伴有发热、烦躁不安、乏力等全身症状

D.吸气、呼气均有困难,并有声嘶、犬吠样咳嗽、喉喘鸣及高热、精神萎靡、皮肤苍白、脉搏细速等全身中毒症状,胸部听诊两肺可有干、湿啰音

E.有喉痛、咽喉异物感及声音嘶哑等临床症状,并有风湿或类风湿病史

题型:问答题

目标管理是一种常用的分析组织目标的方法,它包括四个共同的因素,下面不属于这四个因素的是()。

A.明确目标

B.规定期限

C.分析行动

D.反馈绩效

题型:问答题

财务控制的目标包括()。

A.实现企业价值最大化

B.保护资产的安全与完整

C.保证财务信息的可靠性

D.遵循有关财务会计法规

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