"After a federal election, the party or coalition of parties with the second largest number of members in the House of Representatives forms the Opposition, whose leader is called the Leader of the Opposition."
Australian Citizenship Test gives you access to many more tests than just the one practice test available on the government website. That official sample test is good for giving you an idea of what to expect on the real test. But it can't help you prepare fully. Nor does reading the Australian Citizenship: Our Bond material alone.