Given the task definition and input, reply with output. This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.

Passage: On the 1st of January 1901 the nation-state of Australia officially came into existence as a federation. The Australian continent was colonised by the United Kingdom in 1788, which subsequently established six, eventually self-governing, colonies there. In the 1890s the governments of these colonies all held referendums on becoming a unified, self-governing "Commonwealth" within the British Empire. When all the colonies voted in favour of federation, the Federation of Australia commenced, resulting in the establishment of the Commonwealth of Australia in 1901. The model of Australian federalism adheres closely to the original model of the United States of America, although it does so through a parliamentary Westminster system rather than a presidential system.
What happened on January 21st 1901?