Hello,

Yes you can do bachalor of arts ( BA) after completing your diploma in mechanical engineering. It's totally your choice. But you can't join there as a lateral entry. You have to starting from first there. You can only take admission as a lateral entry in BTech course.

Also you can join distance study in BA course. But most of the college doesn't offer for admission with our 12th a diploma student. But you can find some colleges those are offer for admission of diploma students. So you have to choose first that you want to regular study or distance mode study. Then you can choose the college in Karnataka.

All the best.