Are sets arranged in ascending order by default?

Set order arrangement.

No, Sets aren’t arranged in ascending order as they are odorless

The default ordering of SQL is ascending. If you do not specify the type of sorting you want on the result of the query it gives the result in an ascending manner. If the roll_no has data like 1,2,3,4,8,9, etc. then 1 will come first followed by 2,3,4 etc.

Not all sets are ordered. At the same time there are some text book examples of ordered sets. One of the first examples you find is set of natural numbers.