Thanks Sean Lange for your reply.

1) Yes you are correct the rowcount should be set back to 0. So I have modified the query to below

SET ROWCOUNT 1

select * from employees order by id desc

SET ROWCOUNT 0

2) Also it won't work when you are setting the identity(100, -1) value to negative value.

3) For this question (If a table is having only one identity column how can we insert records into this table?)

I know this is pointless to have a table with only one identity column and there are no other columns.

However the interviewer trys to confuse the person with such question as he may have never tried it.