If I do a 301 redirect from Google Webmaster then will Google take my old domain as my new domain ? I mean, my old domain is www.hackinguniverse.org but I want to change my domain as well as name because I have to get approved for Google AdSense and with having the word "Hacking" .. I now it is quite impossible to get approved for AdSense. But by 301 redirect is it sure that Google will not take my site as duplicate content? Please help.
No, a 301 will direct Google (& other search engines) to your new site for indexing. You can help by making a webmaster tools change of address request.
Matt Cutts from Google has more details on Google's Webmaster tools blog.
It turns out that there is more than one way to perform a redirect, and they are not all created equal. There are two major types of redirects that can be implemented, tied specifically to the HTTP status code returned by the web server to the browser. These are:
301 moved permanently
This status code tells the browser (or search engine crawler) that the resource has been permanently moved to another location, and there is no intent to ever bring it back.
302 moved temporarily
This status code tells the browser (or search engine crawler) that the resource has been temporarily moved to another location, and that the move should not be treated as permanent.
Both forms of redirect send a human or a search engine crawler to the new location, but the search engines interpret these two HTTP status codes in very different ways:
When a crawler sees a 301 HTTP status code
It assumes it should pass the historical link juice (and any other metrics) from the old page to the new one.
When a search engine crawler sees a 302 HTTP status code
It assumes it should not pass the historical link juice from the old page to the new one.
In addition, the 301 redirect will lead the search engine to remove the old page from its index and replace it with the new one.
See also The Art of SEO [specially Chapter 6]