CBSE

Hello Anuj,
You are eligible for appearing in IIT JEE 2018, but according to the eligibility criteria for admissions in various IITs, NITs and CFTIs you are not eligible for admission in these colleges. You need at least 75% in class 12th for being eligible to get admission in these colleges.
Do not worry, you can use your scorecard for admission in various good private colleges also. Many good colleges also take admissions on the basis of JEE Mains scorecard. So, don't lose hope.
Hope this will help you.
Best of luck.

Hi Deepa,
In B.Sc maths or any UG course, you will get only one subject i.e. basic Tamil in the first year and that can be easily cleared as its only basic Tamil and while doing B.Sc maths during the examination, you may get two choices, taking one exam in Tamil and another in English so you can choose to take the exam in English. Tamil is not compulsory.

Hello Niveen
In your class 12th exam question are only from 12th Syllabus but if you wants to score good in engineering entrance exam so covering 11th portion in necessary here are the few important topics which you can cover to score good marks
Mathematics
Conic Section, Andhra Pradesh&GP, Limits, Permutation & Combination
Physics
Gravitation, Sound Wave, Fluid Mechanism
Chemistry
Chemical Bonding, Thermodynamic, Equilibrium, Hydrogen, General Organic Chemistry, States of Matter.

Yes, you can give improvement exam next year as a private candidate. But, if you wants to be eligible for IIT, then you have to give the exam for at least 5 subject. Only then, you are eligible to take admission in IIT or any state college for B.Tech after class 12th.
All the Best.

Hello Bolenba,
Yes, CSE is one of the most preferred branches of engineering, due to its very wide scope and better job opportunities. Here is a link to get the details of top CSE colleges.
https://www.google.co.in/url?sa=t&source=web&rct=j&url=https://www.shiksha.com/b-tech/ranking/top-computer-science-engineering-colleges-in-india/46-2-0-0-0&ved=0ahUKEwijq5mLrMjWAhUITY8KHbNfBkQQFghHMAM&usg=AFQjCNHlO_caCZai8SaW43-vMkaRL4iRkg

NEET is not related to mathematics.