Science

you can get admission in private colleges

many universities offer fs course. you just pass your +2 with vood marks from Science stream and apply for the course.

for ias Science is not necsssary. but you should have knowledge about basics. any one from any field can apply for it

b.sc agriculture is better choice

1) petroleum is not a core engineering. branch
2) it is mix of core branches like mechanical,chemical . .
3) it's rarely available branch(say one college in one state)
4) I think, no course available in diploma level
5) so complete Your +2 pcm, and try for be/B.Tech pet.
6) use internet/Google for availability of courses

1) if u miss B.Tech this year, don't stop study, do B.Sc and try for B.Tech. next year. by taking long term coaching
2) if done B.Tech, there is no need Masters
3) doing B.Sc needs MCA later
4) doing B.Tech or MCA or polytechnic diploma only make u engineer
5) if u r interested in computers, do BCA/B.Sc.IT

it good is too 10 in india

by B.Tech lateral entry