练习册

  • 练习册
  • 试题
    6． 调制解调器 【查看更多】

     

    题目列表(包括答案和解析)

    The modem（调制调解器）is used for ____ a computer ____ a telephone line.


    1. A.
      connect; with
    2. B.
      connecting; and
    3. C.
      connect; to
    4. D.
      connecting; with

    查看答案和解析>>

    实验室用铜制取硫酸铜，将适量硝酸分多次加入到铜粉与稀硫酸的混合物中，加热使之反应完全，通过蒸发、结晶得到硫酸铜晶体。
    （1）为了节约原料，硫酸和硝酸的物质的量之比最佳为：    ；为了吸收该反应中产生的尾气，请选择下列中合适的装置       。

    （2）为符合绿色化学的要求，某研究性学习小组进行如下设计：
    第一组：以空气为氧化剂法
    方案1：以空气为氧化剂。将铜粉在仪器B中反复灼烧，使铜与空气充分反应生成氧化铜，再将氧化铜与稀硫酸反应。
    方案2：将空气或氧气直接通入到铜粉与稀硫酸的混合物中，发现在常温下几乎不反应。向反应液中加少量FeSO4，即发生反应，生成硫酸铜。反应完全后，加物质甲调节pH ，铁元素全部沉淀（一般认为铁离子的浓度下降到10-5mol·L-1，就认为沉淀完全），然后过滤、浓缩、结晶。
    已知：Ksp[Cu((OH)2]≈10-22， Ksp[Fe((OH)2]≈10-16,  Ksp[Fe((OH)3]≈10-38
    请回答下列问题：
    如开始加入的铜粉为3.2 g，最后所得溶液为500 mL,溶液中含有铁元素0.005 mol。
    ①方案1中的B仪器名称是       。
    ②为了使铁元素全部沉淀，应调节pH至少为_________。
    ③方案2中甲物质可选用的是             。
    A．CaOB．NaOHC．CuCO3D．Cu2(OH)2CO3 E、Fe2(SO4)3
    ④反应中加入少量FeSO4可加速铜的氧化，用离子方程式解释其原因        。
    第二组：过氧化氢为氧化剂法
    将3.2g铜丝放到45 mL 1.5mol·L-1的稀硫酸中，控温在50℃。加入18mL 10%的H2O2，反应0.5h，升温到60℃，持续反应1 h后，过滤、蒸发浓缩、减压抽滤等，用少量95%的酒精淋洗后晾干，得CuSO4·5H2O 10.5g。
    请回答下列问题：
    ⑤反应时温度控制在50℃~60℃不宜过高的原因是         ，
    ⑥本实验CuSO4·5H2O的产率为         。

    查看答案和解析>>

    Mails, games, music, news, chat rooms and shopping! The Interent is part of our life today. It’s easy to get onto the Internet. The only thing we need to do is to use a modem(调制解调器) which is used for connecting a computer to a telephone line. The Internet is changing and growing all the time. More and more people have computers and use the Internet. Using the Internet means surfing the World Wide Web(That’s the “WWW” you always hear about). The Internet has a large number of websites(网站). They are the places where you go to get information and do things.

    Where do these websites come from? They are made by web designers. What happens when you click on a word or a picture? You are sent to another page. It’s all because of the web designers. Web designers do a lot of work by using a computer programming(程序编制) language.

    Is web design all about computer programming? No, it’s about making something new. Web designers must imagine a lot when they are making a website. It must look good and be fun to use. A big part of web design is art. They choose the best pictures and colors to make the website look good. They also write the things that you see on the website. An important part of their job is to share ideas with the website manager about how to design the website well.

    (   )36.More and more people are using the Internet because _____.

                A.it’s easy and useful

                B.it’s changing and growing

                C.websites are designed quite well

                D.people can design a computer

    (   )37.Which of the following is WRONG?

                A.“WWW” means “World Wide Web”.

                B.There’re a few websites on the web.

                C.The Internet has changed people’s lives.

                D.We can do things like shopping on the Internet.

    (   )38.Web designers must _____.

                A.write all the articles on the website by themselves

                B.follow the managers’ ideas

                C.be creative

                D.share computer with the website manager

    (   )39.It’s possible for us to change websites just by a click because of _____.

                A.the modem’s help

                B.the telephone line’s help

                C.the web designers’ work

                D.the website manager’s work

    (   )40.The last paragraph is mainly about _____.

                A.computer programming language

                B.the web designers’ work

                C.how to make a website

                D.how to use the Internet

    查看答案和解析>>

    Mails, games, music, news, chat rooms and shopping! The Interent is part of our life today. It’s easy to get onto the Internet. The only thing we need to do is to use a modem(调制解调器) which is used for connecting a computer to a telephone line. The Internet is changing and growing all the time. More and more people have computers and use the Internet. Using the Internet means surfing the World Wide Web(That’s the “WWW” you always hear about). The Internet has a large number of websites(网站). They are the places where you go to get information and do things.
    Where do these websites come from? They are made by web designers. What happens when you click on a word or a picture? You are sent to another page. It’s all because of the web designers. Web designers do a lot of work by using a computer programming(程序编制) language.
    Is web design all about computer programming? No, it’s about making something new. Web designers must imagine a lot when they are making a website. It must look good and be fun to use. A big part of web design is art. They choose the best pictures and colors to make the website look good. They also write the things that you see on the website. An important part of their job is to share ideas with the website manager about how to design the website well.
    小题1:More and more people are using the Internet because _____.
    A．it’s easy and useful
    B．it’s changing and growing
    C．websites are designed quite well
    D．people can design a computer
    小题2:Which of the following is WRONG?
    A．“WWW” means “World Wide Web”.
    B．There’re a few websites on the web.
    C．The Internet has changed people’s lives.
    D．We can do things like shopping on the Internet.
    小题3:It’s possible for us to change websites just by a click because of _____.
    A．the modem’s help
    B．the telephone line’s help
    C．the web designers’ work
    D．the website manager’s work
    小题4:The last paragraph is mainly about _____.
    A．computer programming language
    B．the web designers’ work
    C．how to make a website
    D．how to use the Internet

    查看答案和解析>>

    阅读理解。
         Mails, games, music, news, chat rooms and shopping! The Interent is part of our life today. It's easy to get
    onto the Internet. The only thing we need to do is to use a modem (调制解调器) which is used for connecting
    a computer to a telephone line. The Internet is changing and growing all the time. More and more people have
    computers and use the Internet. Using the Internet means surfing the World Wide Web(That's the"WWW" you
    always hear about). The Internet has a large number of websites (网站). They are the places where you go to
    get information and do things.
         Where do these websites come from? They are made by web designers. What happens when you click on
    a word or a picture? You are sent to another page. It's all because of the web designers. Web designers do a
    lot of work by using a computer programming (程序编制) language.
         Is web design all about computer programming? No, it's about making something new. Web designers must
    imagine a lot when they are making a website. It must look good and be fun to use. A big part of web design is
    art. They choose the best pictures and colors to make the website look good. They also write the things that
    you see on the website. An important part of their job is to share ideas with the website manager about how to
    design the website well.
    1. More and more people are using the Internet because _____.
    A. it's easy and useful
    B. it's changing and growing
    C. websites are designed quite well
    D. people can design a computer
    2. Which of the following is WRONG?
    A. "WWW" means"World Wide Web".
    B. There're a few websites on the web.
    C. The Internet has changed people's lives.
    D. We can do things like shopping on the Internet.
    3. Web designers must _____.
    A. write all the articles on the website by themselves
    B. follow the managers' ideas
    C. be creative
    D. share computer with the website manager
    4. It's possible for us to change websites just by a click because of _____.
    A. the modem's help
    B. the telephone line's help
    C. the web designers' work
    D. the website manager's work
    5. The last paragraph is mainly about _____.
    A. computer programming language
    B. the web designers' work
    C. how to make a website
    D. how to use the Internet

    查看答案和解析>>


    同步练习册答案