B.Sc

go with your favourite one and choose teaching line.
for private jobs go with chemistry.

Try to crack CDS( http://upsc.gov.in/general/cds.htm)
or try to crack SSC.

You need to have completed your B Tech or BE in the streams like electronics, electrical, computer Science or mechanical engineering. You need to have aggregate score of 60% and above throughout your career.
Indian citizens who are not more than 35 years of age can apply; however, there is some relaxation in the age limit for candidates from the reserved categories. The candidate can appear in the written test during the final year of B Tech or BE course.

you can go in teaching field by doing b.ed(2 year) after b.SC . and doing master after b.ed will leads to a better post.

B.tech is more valuable in these days