Ph.D

1. Anna University.
2. Madurai Kamaraj University.
3. Annamalai University.

Please refer to the link provided below for a list of courses offered by the university in question. You should be able to navigate to a Ph.D in Chemistry using the filters on the web page.
https://www.shiksha.com/university/gitam-university-visakhapatnam-24065

Please refer to the link provided below for a list of top colleges which offer Ph.D courses in management in India. You should be able to use the filters on the webpage to navigate to a college of your choice.
Link: https://www.shiksha.com/mba/ranking/top-mba-colleges-in-india/2-2-0-0-0

A candidate must have a 4 year or equivalent undergraduate degree from an accredited university. A candidate must have a prior undergraduate or graduate degree in a major with a substantial background in computer science & engineering. Those candidates who have completed Masters degree from a recognized university with above 55% marks are eligible for Ph.D course.
Please refer to the link provided below for a list of top colleges to pursue a PhD in computer sciences in India:
Link: https://www.shiksha.com/engineering/colleges/ph-d-computer-science-engineering-colleges-india

I doubt there should be any problem if you are pursuing a different subject in your PhD or M.tech. The most you can do is concentrate on your current studies and make sure you perform well in the current course.