The question does not make sense. All of the states of Australia share a border with another state. Even Tasmania, the island state, shares an actual land border as well as a water border with another state.
Mary land
Asia is the continent that has the longest land border.
Sweden's longest land border is with Norway. Finland is the only other country with which Sweden has a land border, although only a narrow waterway separates Sweden from Denmark.
There is no Australian state which shares a border with all other states. No state except for Victoria shares a land border with Tasmania. South Australia shares a border with all mainland states and the Northern Territory.
South Australia's land border is 3 185 km long.
The Canada USA border 5525 miles long
If you simply check a map of the world (google maps is a good source) you will see that the longest land border that Chile has is with Argentina.
America and Canada.
venezouela
Not in land border but in water border, yes.
South Australia borders the most states and territories in Australia. South Australia shares borders with Western Australia, the Northern Territory, Queensland, New South Wales and Victoria.