I have installed mango SDK in my machine and I want to create an application which runs on both Windows Phone OS 7.0 and Windows Phone OS 7.5 devices. Also I need to implement many of the mango features in the same application. Is it possible ? if yes please tell me how to do the version checking, because based on the version we need to implement the mango features.
You'll have to maintain two different versions. You can't compile one XAP that supports both versions at the same time.
The Mango APIs are only available when compiling with the 7.1 SDK. And as such, you can't do in-line checking in the code.
But it's rather pointless, as there's almost no users left that haven't upgraded to Mango, and all new phones ship with Mango.