Dear Akshaya,

Yes, everything is even if you have studied only the important chapter of Physics and Chemistry but you have to do mastered in that which is quite impossible, so try to grab each and every possible knowledge from that important chapters and also try to know atleast some basics pf that leftover chapters, it would be more beneficial if you do like that, even most of the students follow this strategy. Now its totally up to  you, which chapter you want to skip and which chapter you have to study the most.

Best Of Luck!!!