Official – Commonwealth of Australia
Other – Australia
Citizens – Austalians
Capital – Canberra
Language – English (there are also aboriginal languages)
Radio – ABC-Radio Australia – http://www.abc.net.au/ra/

Why English? – Australia was settled by people from Great Britain and Ireland – often forced there for committing crimes, or being in debt, or agitating for Irish independence. The aboriginal population was push away from these European settlements.