Hi there,
Hope you are doing well.
If your sole target is to get a good placement for the college, then you should prefer EIC over Chemical since it is one of electrical Engineering's core branch and many big companies hire from EIC.
On the other hand, if you have a research-oriented view, then you should go for Chemical since it has better options in research and for further studies.
Whereas Mechatronics is a branch which has both the scopes, placement as well as research.
But the base of Mechatronics is not so strong in India and for a nice package you would have to complete your MTech or MS.
BTech in  Mechatronics alone won't be able to get you a very good package.

Hope it would help
Thank You