English honours-74%,12th(commerce)-70%,10th-86%.can arts background in graduation hinder my chances of getting in top b-school?

No it won't hinder your admission in too B school in anyway. On the other side it will act as your advantage as top B-schools want students diversity. As most of them enrolling are engineers so as to promote diversity they give non engineers extra marks in aggregate score. Also you can get call on a lower percentile as compared to engineers.

But I can see that you have an average academic background so you need to aim for a high percentile. Like aim for above 98 percentile in order to get calls from old IIMs. Though percentile is notbtbe only criteria there are also many other parameters such as 10th, 12th, graduation marks, work experience, engineer or non engineer, gender which carry different weightage in different colleges to make an aggregate score.

As less than 2 months are left for CAT exam so you should brush up with your basics and give up lots of mock test and analyse them. Analysing will help you in overcoming your mistakes and come up with a  strategy to attempt your paper which will definitely help you in improving your marks and percentile.

All the best!!

Your graduation course will be an advantage while applying for any B-School.

Top B Schools are constantly focusing on increasing academic and gender diversity on their campus and hence they give extra marks for Commerce, Arts, Medical and other non-engineering background students during the admission process.

Hence you should focus on your preparations and try to get a good percentile in various MBA entrance exams.