CBSE 12th

Hello,
Your class 12th marks are good to apply to any of the undergraduate programs.
For MSc you must complete your graduation in any of the disciplines with a minimum of 50% score.
KS School of Bussiness Management is affiliated to Gujarat University. It was established in the year 1993. It offers integrated MBA ( 5 years duration) for the 12th passed students and MSc (2 years duration) for graduates.
KSSBM offers two specialisation for its MSc program.They are -
1. Computer Science
2. Information Technology
Eligibility Criteria
The admission is merit based. Students in the final year of their undergraduate program can also apply. They must secure a minimum of 50% in their graduation to be eligible for admission. The student must have completed their graduation in the relevant subject from a recognised university.
How to Apply
1.The application mode is online. So you can visit the official page of Gujarat University and click on 'student login'.
2.Select NEW REGISTRATION.
3. Fill all the details correctly. At the end cross check for errors.
4. After completing the Registration process, Application form will open. Fill the form carefully.
5. You will be asked to fill the college and course of your preference.
6. Tap on SUBMIT button.
7. Your form has been submitted.
Tip: keep your Registration Number, Serial number and Pin Number saved at some place for future reference.

Hey, while your academics are bad you can still salvage them with a good CAT percentile.
While Tier 1 Institutes are tough to crack at this marks, you can easily get into tier 2 colleges such as below with 90-95+ Percentile in CAT:
K. J. Somaiya Institute of Management Studies and Research, Mumbai
Institute of Rural Management Anand, Anand
Symbiosis Institute of International Business (SIIB)
T. A. Pai Management Institute,
Symbiosis Institute of Business Management, Bangalore
International Management Institute (IMI), Delhi
Great Lakes Institute of Management, Chennai
Great Lakes Institute of Management, Chennai
Indian Institute of Management (IIM) Ranchi
Institute of Management, Nirma University
Indian Institute of Management (IIM) Raipur
Indian Institute of Management (IIM) Tiruchirappalli
Indian Institute of Management (IIM) Rohtak
Indian Institute of Management (IIM) Udaipur
Goa Institute of Management (GIM), Goa
Indian Institute of Technology Madras (IIT Madras), Chennai
Xavier Institute of Management & Entrepreneurship, Bangalore
Symbiosis Institute of Media and Communication, Bangalore
Institute for Financial Management and Research (IFMR), Chennai
Institute of Management Technology (Nagpur)
University Business School (UBS), Panjab University, Chandigarh
Indian Institute of Forest Management (IIFM), Bhopal PG Diploma (Forest Management)
National Institute of Technology, Tiruchirappalli

The Top 21 courses you can choose after 12th Commerce are given below.
B.Com (Honours)
B.Com (in Business Economics)
BA Economics
BBA (Bachelor of Business Administration)
BAF (Bachelor of Accounting and Finance)
BBI (Bachelor in Banking and Insurance)
B.Sc (H) Statistics
CS (Company Secretary)
Language courses
BA LLB
Bachelor of Business Studies
BA (Honours) in Business Economics
B.Com (Pass)
BA Honours (English)
BCA (Bachelor of Computer Applications)
BFM (Bachelor of Financial Markets)
ICWAI (Institute of Cost and Work Accountants of India)
BStat (Honours)
Mass Communication/Journalism
BA Visual Communication
BFA (Bachelor of Fine Arts)
A few courses that come with a Maths subject are given below. B.Com (Honours)
B.Com Accounting and Taxation
B.Com Statistics
B.Com in Management Accounting & International Finance
B.Com in Accounting
B.Com Applied Economics
B.Com Banking & Finance.

First of all, you have not mentioned a particular course which you want to pursue. However, For B.Sc. (Hons. ) (Mathematics, Computer Science, Physics) Eligibility Criteria: Students must have passed a 10+2 or equivalent examination from a recognised school or board. Eligibility Criteria for B.Sc. in Physics: Applicant must have passed 10+2 or equivalent examination from a recognised board. There is a common entrance examination for both the B.Sc. (Hons. ) programs. You need not select your course at the time of applying. The choice can be made after admission. For Ph.D. , students should write the Joint Entrance Screening Test (JEST). For more details, you may visit the Shiksha CMI page. (https://www.shiksha.com/university/Chennai-mathematical-institute-cmi-2449/admission). I hope this will help you.