hi,

see iit kharagpur offers bachelors course in bachelor of technology and bachelor of architecture.  however  students who has completed b.sc and wants to pursue m.sc may apply for iit jam exam to admission in relevant masters course.

see you can be a scientist after studying engineering / architecture/ general  science course. you have to do masters along with phd to get scientist level position , depends on the criteria of organization. so decision is yours which path you want to take.