Hi Aspirant

The most important thing is which branch interests you the most , whether it is CS or Chemical . Both are very different branches with different sets of opportunities.

As far as getting an MS in a reputed University is concerned, that will depend on the projects that you take up and your grades and your level of preparation in the four years of College.

The IIT tag might help a little but the above mentioned things are the most important.

Hope this helps. All the Best.