Hello aspirant,  

Usually no marks are given for unattempted question. But bonus is given in cases where question is wrong or ambiguous or answer does not match with the question. In that case bonus marks are awarded to all students. So even if you have not attempted the question you will be awarded with marks. But in some cases where two answers are correct, in that case only those students who attempted any one of the answers will be given marks.Those students who attempted wrong answer is given negative mark.

Best of luck!!