Hello Padmanabha Raula, 

Look, every college even Chandigarh University has certain criteria for selecting candidates. They want minimum 60% in PCM.  So this is compulsory. 

However, generally, there are three ways to get admission into any college. First through JEE main score, College entrance exam and through management quota. Now as you have mentioned your rank is 904 in JEE main, which is pretty good. So you should immediately apply using your JEE main score. You can check following to register in this college.

http://www.cuchd.in/admissions/ 

Beside this, I would also suggest you to keep searching for more colleges now, as no college has started their counseling yet. Keep your option open for now and keep reading the reviews of other students as it will help you to know more about the college education system and placements. 

Hope you find this information useful. Have a great future ahead.