Chemistry Spl

You won't be eligible for admission into IIT (JEE Advanced) as Chemistry is considered necessary requirement there.
But you can take admission into NIT, IIIT, etc. (JEE Mains) as in place of Chemistry they also accept Biology marks.
You can check JOSAA's official website where they clearly mentioned that admission into BTech from NIT,IIIT,GFTI, etc. requires one to pass 10+2 board examination with Physics and Maths as compulsory subjects, with any one extra subject from these:- Biology, Biotechnology, any Technical Vocational subjects such as Computer Science.
This change in requirement was brought recently via a new rule from AICTE.
But IITs refused to accept this change, so you still require PCM as eligibility criteria for IITs, i.e. JEE Advanced.
Hope this helped.

It depends on how to keep your mind into that subject
Let's say a person with an interest to Chemistry may find the subject interesting and understandable but someone who doesn't have much interest to reactions and such sort of things may find it boring or at most hard to understand. As you know Learning Chemistry takes time that's the reason it split into sections
1. Dig Deep on practice problems - You will never SEE an exam problem that looks exactly like a practice problem, so doing every problem possible is not a good strategy
2. Do the reading and warm up problems before lectures or classes whatever you are in right now
3. (Important Point) Ask lots and lots of questions - If you are reviewing material on your own write these questions down. If you can answer them on your own, great. If you are stuck, then take them along with you to your classes or school or college lectures.
4. Study more efficiently - Quality matters over quantity in Chemistry so rubbish writing doesn't help much.
5. While dealing with Organic Chemistry always refer to videos or any references you can get even a good ex- student can help. These are just my opinion but the results and the efforts put to study are upto you. So All The Best!

Following is the eligibility criteria-
Chemistry for three years/six semesters
or
Candidates having a Bachelors degree without (Major/Honours) must have the concerned degree with (a) Chemistry as a subject for three years/six semesters, (b) Minimum 2 (Two) courses in Mathematics (c) Minimum 2 (Two) courses in Physics
or
In B.Sc. /BS, at least six Chemistry subjects for three years/six semesters. At least FOUR courses as general elective (GE) from the following list of subjects taking at least one Physics and one Mathematics course: Physics Mathematics, Biology Biochemistry, Computer Science, Biotechnology. The student should study one Mathematics and one Physics subject during his/her course of study. This is what most of the IIT's demand. 12th subject is not asked.