8. While doing an ascending order sort on a column having NULL values, where does
the NULLs show up in the result set? At the beginning or at the end?

Ascending order sort - NULLs come last because Oracle treats NULLs are the largest possible values

Descending order sort - NULLs come first

* How to make NULLs come last in descending order sort?

Add NULLS LAST to the order by desc clause

Eg: select col1 from table1 order by col1 desc NULLS LAST