On This Day: 29 June 1972 USSR launches ---------- 2 into earth orbit (549/200,000 km) ?

Questions

Computers - mhz stands for________?

Computers - on "Windows 95/98",what application can you use to see all the files that you have on your computer?

Computers - to erase data or files from your computer is to________?

Computers - to transmit files from a central computer or server to another is called_______?

Computers - what do you call a "file extention" given to "batch files?