No, you do not need to do that. Earlier versions can coexist with newer ones. Only exception is sub-versions. For instance, 4.5 version is available for download and when you install it it will replace 4 version but it will keep untouched 1, 2 and 3.5.
The current version of the .Net Framework is version 3.5 Service Pack 1.
Yes, CLR version changes with .NET framework Version since the API changes with version enhancement.
If you have lost or damaged your copy of Internet Explorer on Windows, you can download the latest version of Internet Explorer (and some other earlier versions, at that) at the Internet Explorer home page; a link to it can be found in the related links.
Current version of the NET Framework is NET Framework 4 .
Trashbin it
You can always fix this by installing the chrome again. The earlier version could have a bug or error.
3.5sp1
3.1
You usually only need older versions of the .NET framework installed if you have an old application which requires an older version of the framework. In general, you should be able to run most (if not all) applications using the latest version.
iTunes 9 requires QuickTime 7.6 or later. If you are running an earlier version of QuickTime you will need to update it. The iTunes installing process should let you know if you need an update but will not do it automatically.
Net framework is a software framework produced by Microsoft. It runs on Microsoft windows. It helps programmers produce software that works with Microsoft products. It was first released in 2000, and the latest version (version 4) was released in 2010.
check version in C:\WINDOWS\Microsoft.NET\Framework