NIT

Yeah ofcourse, It's very good when we compare to some NITs. 

National Institute of Technology is well reputed for MSc in Physics. Strong academic programmes and faculty from various well experience backgrounds make the college popular among studnts. It is a full-time two-year course, intended to cover most of the aspects in Physics ranging from basic concepts to research level. Furthermore, students are provided a space with modern equipment and setup that is necessary for carrying out experiments and research work.

Yes you can combine both home state quota and obc reservation together. At this score u are not able to get top 10 colleges whose admission criteria is jeemain. For good college you must need to improve your marks .

It is possible to join NIT with less than 75 percent marks in 12th, but it is very difficult. NITs are some of the most competitive engineering colleges in India, and they typically have a cut-off of 75 percent or higher for admission.

No, you cannot get admission to the first year of B.Tech in IIT or NIT after completing a Diploma. 

Chances of getting NIT Jamshedpur and NIT Sikkim are good enough under the asked category.