No, one can not switch from iMSc. to B.Tech after the first year. The first year courses of both these programs are entirely different. But one can change one’s branch within the iMSc. to and from Physics/Chemistry/Maths.
Having answered this question, here are the good aspects of iMSc. at SVNIT-
The iMSc. program is no less than any B.Tech branch of SVNIT. With hardwork and dedication, one can do wonders with this degree.