Those are two separate and totally unrelated concepts.
Linux and Unix are considered multi-user systems because they support separate user accounts with different levels of access privilege. A single-user system may have more than one "account", but there is no administrative difference between them.
Linux and most modern versions of Unix are multiprocessing operating systems because they support more than one processor in a system and can allocate processes to different processors.
If you are interested in the exact details of how this is accomplished you should check any textbook on Operating Systems for how it is done. The answer is beyond the scope of this web site, which is for short, concise answers (which cannot be done for this topic).
1.it is the parallel processing
2.complexity & consumption of time reduces
Unix has the capability of running more than one task at a time (or seeming to), which makes it multi-tasking.
Because that was a design goal of the operating system.
That was one of its design goals.
Yes, although to use multi-programming effectively your hardware needs to have multiple CPUs.
yes
Windows, Linux, Unix.
Not really a true statement; both Windows and UNIX have multi-tasking and multi-programming capabilities.
No difference, really. Unix is an OS (Operating System)
unix.
UNIX is a command-based OS. In contrast, Windows is a menu-based OS.
kernel is everything in unix os
Why do you believe this is necessary? What OS are you talking about?
LINUX and UNIX are vendor independent OS
Hewlett-Packard Unix. It is a series of computers that runs the Unix OS. Most people recognize the HP as a computer company in the acronym. This their version with the Unix OS.
Unix is a specification. Mac OS X is a certified implementation of Unix. This like asking "What is the difference between a turtle and a red-eared slider."