Hello,

If you interested in BTech then you can join engineering college. Because you have mathematics physics and chemistry. But you mentioned above that you will be become a IAS officer. Then you have to give UPSC examination. So after completing BTech you can give the UPSC examination. But you have to prepare the UPSC syllabus with your BTech courses otherwise you can take a break for 1year examination preparation after completing your BTech. Actually you can choose anything in your bachalor degree but you have to prepare yourself for UPSC examination then you will get qualify the Mains and prelim examination.

All the best.