Hello Aspirant! Physical Chemistry in JEE Main is equally important than any other topic as questions come from each and every topic. But physical chemistry probably carries less weightage than organic and inorganic chemistry. Organic chemistry hold the most weightage in chemistry. But it can also depend on the session of your exam and on your luck as it may vary. Someone gets more questions from organic and someone gets more questions from inorganic or physical topic. So it would be better if you study everything thoroughly and not leave any topic behind.
Hope this helps.