hello,

you have not mentioned with respect to what term you are asking. if you are asking with respect to board exam then all chapter are important.

with respect to entrance exam like JEE, NEET , you can prioritize chapter based on previous years data. this will only help if the prediction works. as no one can give garuentee that it will work.

for next year, it is declared by the official authority that syllabus will be decreased by 30% due to delay in education process and session start time got delayed by a big time.

you have to update yourself accordingly.

In generic term, all the chapters are important and that is why it is kept in the subject so that you will learn what this term is or object is. how it changes world and what it contributes to?

it is learning process. if you look in perspective of score, then you can't gain knowledge. You will forget eventually after completion of exam.

Hope it helps!