Yes, JEE exam is totally objective however it includes integer type questions as well which test your subjective approach as welll. As far as conceptuality is concerned JEE exam is not totally conceotual. It tests you reasoning as calculation skills as well. So an all round preparation is required to crack JEE exam.
Yes, NCERT books are sufficient for making the basic concepts but just the basic knowledge will not be enough to crack JEE exam . You need to study elaborate concepts as well from different books prescribed for JEE.
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