Chemistry Spl

Do you have maths as additional subject? There is a way to join the institute of ISRO (IIST- Thiruvananthapuram) by the score of JEE Mains and advanced. If not possible then after graduation from engineering colleges, you can join ISRO by appearing in exams and interview.
In case you don't have maths, then most probably you have to pursue M.Sc. For details check ISRO's website and best wishes for you. I am also passionate for ISRO.

There are companies which recruit students after completing B.Sc in Chemistry, but they are very few. You will have to complete your Master's degree as well.

Chemistry is basic sciences course while biotech comes in life sciences difference in the two lies in specialisation also if you wish to teach at school level some day your biotech degree won't make you eligible for it but chemistry will. Otherwise both have good scope after msc in the subject as university teacher or in industries as associate of resarcher.

Majority of Universities or college admission is based on Entrance Examination. You are advised to appear in BCA Entrance Examinations in several Universities to increase your chances of admission in BCA degree course.