CBSE 12th

I know how painful it is to go through NCERT.
It doesn't matter whether you are the topper of your class or an average student scoring a little more than 70%. The books I've mentioned below will surely boost your marks. I have myself used these books and secured more than 92% in CBSE boards. 6 out of 8 friends, whom I suggested these books have secured more than 90% marks in CBSE board examinations 2017.
How many books should you buy?
I will strongly recommend you to follow only one reference book at a time. It is so because different authors have different ways of making you understand things. However, for mathematics, you are free to use as many books as you can.
Can't wait anymore? Let's start:
Pradeep's Fundamental of Physics and Chemistry
Excellent collection of numerical problems.
A lot of additional stuff is provided for curious students.
The theory provided really helps you in clearing concepts.
Simple and easy to learn definitions and derivations.
- Buy Physics for class XI
- Buy Physics for class XII
- Buy Chemistry for class XII
- Buy Chemistry for class XII
R.D. Sharma
Wide variety of problems
Some very challenging questions are sprinkled in solved examples.
Each year direct questions are asked from this book.
- Buy Class XI RD Sharma
- Buy Class XII RD Sharma
The books listed above are strictly for boards. You may also want to prepare for JEE Mains and Advanced. You can find those books in Satyam Kumar's answer to What are the best books that can be referred to, for JEE Mains and Advanced for preparation in Physics, Chemistry and Mathematics?
All the best.

After the completion of class 12th in commerce if you are weak in mathematics then you should not study anything which has major subject as mathematics. Besides your mathematics subject in commerce or accountancy subject, you must have some other subject with language subject. If you are good in another theoretical subject then you may go for general 3 years graduation with honours in that subject.
If you are good in English and you are interested in studying a course related to English then obviously you should take admission in English honours. There are so many opportunities after completion of graduation in English. You will get so many good jobs if you are good in that subject. You may try for the job in the teaching field as well as for civil services for which graduation from any stream is required.
After the completion of your graduation, you may go for MBA. If you complete your graduation in English and after that, if you do MBA in HR then easily you will get a good job with a good salary package. In MBA, there is a little bit of mathematics but it is not much difficult. As you got 80% in 12th (commerce stream), you will be able to do the study maths which is included in MBA in HR course.
If you are interested in computer related course then also you may go for that. But for most of the courses, there is some part of mathematics. If you want to totally avoid the mathematics then do not go for computer courses. But if you think that you are weak in mathematics but you can study mathematics as the minor subject then you may take admission in computer related course like BCA and other. First, find out in which theory subject you are interested more and then try to study a course related to that subject. That will be the best option for you.
Best of luck.

As you have done B.Sc in PCM and now you want to pursue your Master's degree in the relevant stream. Before choosing right stream you should know about your interest and dream job you are looking for. Your career option is totally based on these factors as it will provide you satisfaction and stability in your professional front.
Now as courses are concerned, you may go for:
M.Sc in any of the individual subject which you feel you are strong in it because job opportunity varies in Physics, Chemistry or Mathematics. So if you are planning for M.Sc then choose it wisely after analysing job prospects.
You can also go for MBA in various specialisations like international business, HR, Finance, Operations, Retail, Banking, and much more.
You can also move towards pharma industry.
You may move towards Astronomy, it is an emerging field and has a great market demand.
You will be having career in industries like
Agriculture Industry
Testing Laboratories
Forensic Crime Research
Wastewater Plants
Aquariums
Environmental Management and Conservation
Food Institutes
Pharmaceuticals and Biotechnology Industry
Research Firms
Forest Services
Geological Survey Departments
Health Care Providers
Industrial Laboratories
Oil Industry
Biotechnology Firms
Chemical Industry
Educational Institutes
Hospitals
Seed and Nursery Companies
Space Research Institutes
Wildlife and Fishery Departments
So, now do self-analysis as I advise all the students, and then decide what suits you more.
All the best.