You will not receive any notice when it gets terminated, when your app is suspended in the background.
iOS will send a kill -9 signal for your apps progress and you app is just killed, this is the same thing that happens when the user kills your app from the quicklaunch tray.
From the Apple documentation:
Even if you develop your app using iOS SDK 4 and later, you must still be prepared for your app to be killed without any notification. The user can kill apps explicitly using the multitasking UI. In addition, if memory becomes constrained, the system might remove apps from memory to make more room. Suspended apps are not notified of termination but if your app is currently running in the background state (and not suspended), the system calls the applicationWillTerminate: method of your app delegate. Your app cannot request additional background execution time from this method.