2.5year old recovered from runny nose last week.this night he is snoring and i can hear a bit mucus behind nose and not chest.has enlarged adenoids. ?

Maybe??: You cannot see the adenoids directly. They lie above the soft palate. An ENT has either mirrors wherein he can stick them in the back of the throat like a dentist and look forward and see them or better yet a flexible fiber optic tool which hw inserts in the nostril and threads it in and looks forward. It is usually the vibration of the uvula, that hanging piece, that causes the snoring.