Wikipedia
Because all questions with answers in the world present at wiki site.
No. A 'wiki' is any site that uses the wiki system of public creation and editing. Wikipedia is most well known site that uses this system, but that does not mean any site with 'wiki' in, is in any way related to the Wikipedia.
The most well known site using "the wiki way" is probably Wikipedia.com
You can copy Wiki content for use on your own site - BUT - you must acknowledge on your site where the information came from.
Wikipedia is a wiki because the underlying software (Mediawiki) has the features commonly associated with a wiki site. The word wiki comes from Hawaiian for quick and a wiki site allows the content to quickly change since anyone can edit it.
Wiki answers... Answers.com
Yes. Wikipedia is an example of a wiki, a site that can be edited by its users.
WoWWiki, a wiki specifically about World of Warcraft, was launched shortly after the game was released in late November 2004. It moved to Wikia in 2007, where WoWWiki became known as the largest wiki hosted on that site two years later.
The site you are on right now is the largest. It is Wikianswers!
it's classified
No. This is a Wiki site not a chemist.
I honestly do not know where to find a site on wiki cloud computing. However, if I were to guess a good spot to start would be a wiki page for the same name.