Картинка: https://i.imgur.com/KoOAyAw.jpg

The history of the Internet

It’s history

The Internet started in the 1960s. The United States Department of Defense started it because they wanted a computer network to help the American military. In the 1970s scientists worked on it.

Then in the 1980s telephone companies made in possible to communicate on the computer network in many more countries. An international computer language was born, and the Net went worldwide.

What can it do?

You can use the Internet for many things. You can buy a car or a house; you can book a holiday; you can watch a video; you can read an Australian newspaper or a Japanese magazine; you can buy books and CDs from North and South America; you can play chess with a partner in Moscow; or you can just chat to people from all over the world. The list is endless

Объяснение:

Напишите молекулярные и ионные уравнения реакций между предложенными веществами и объясните возможность протекания реакций:

А)  K2CO3   +  2 HCl  =   2KCl  +  H2O   +  CO2↑

    2K(+)  + CO3(2-)  + 2H(+)  + 2Cl(-)  = 2K(+)  + 2Cl(-)    + H2O   +  CO2↑

              CO3(2-)  + 2H(+)  =   + H2O   +  CO2↑

Б)хлорид аммония и фосфорная кислота

NH4Cl   +  H3PO4  ⇄  NH4H2PO4    +  HCl

 Все  ионы  будут  в  растворе  и  реакция  ионного обмена  будет обратимой

                     

В) нитрат железа (III) и гидроксид бария

3Ba(OH)2  +  2Fe(NO3)3   =  2Fe(OH)3 ↓  +  3Ba(NO3)2

3Ba2+ +  6OH(- ) +  2Fe3+  + 6 NO3 (-)  =  2Fe(OH)3 ↓  +  3Ba 2+ + 6NO3 -

                  6OH(- ) +  2Fe3+  =  2Fe(OH)3 ↓

Г) сульфат аммония и гидроксид натрия

  (NH4)2SO4  +  2NaOH =  Na2SO4   +  2NH3↑    + 2H2O

2NH4+   + SO4 (2-) +  2Na(+) + 2OH(-) =  2Na(+) + SO4(2-)   +  2NH3↑    

+ 2H2O

                2NH4+   + 2OH(-)  =  2NH3↑  + 2H2O