I am no Linux expert, but both Oracle Linux and Ubuntu are Linux OS's - so there is a lot of similarity between the two. Pl google for my blog on how to install Oracle Linux on a VM - it is now over a year old and things may have changed since then - but I have documented step by step screenshots that may be helpful
I would go with OEL instead of CentOS - although likely binary compatible, OEL is 'officially supported'.
That said, OEL is just as easy as other distros. It may not support bleeding edge hardware out of the box, because 'Enterprise' distros are often based on older kernels and such.
Could you mention clearly which version of oracle linux is supported for installing oracle 11gR2 database?
I could, but I won't. Instead I will show you how to find out for yourself. Hopefully along the way you will also learn about accessing and using Oracle documentation.
Go to docs.oracle.com
In the "Database" group, click on the database version you want to work with. If in doubt, I'd suggest 11g Release 2, and will assume that from this point. Any other selection and the steps will be similar.
Don't be put off by the fact that the next screen prominently says "Oracle Database 12c documentation". There is also "Previous Releases" followed by 11g Release 2 (11.2). Click that one.
On the next screen, on the left-hand navigation area, click the "Installing and Upgrading" link.
Now you should see an entire grouping of "Linux Installation Guides".
Select "Database Installation Guide for Linux" (click "html")
Click the link for "Preinstallation Tasks"
Click the link for "Checking the Software Requirements"
See the listed OS's under