Loyola College

Absolutely, it will be Loyola because it has world wide recognition.

Loyola will be a great option because it ranks among top 5 colleges in India. Also, you are a resident of Chennai, so it's a good idea.

The admissions are closed for the academic year 2017-2018 for B.Sc in physics.

Placement wing:
Placements in our college are relatively better than other colleges our city. But most of the placements are for the students who are studying computer science in their Bachelors course.
Remarks:
Our college has a huge alumni network. Many of the senior students still interact with us and we share our experiences with our juniors. Our alumni also consisted of many prominent personalities of our state, so I must say that our college has a vast alumni network.

For B.Sc physics, you should have chosen physics, chemistry, maths and any other subjects. You need to have a good score in 12th board exams. There is no particular cut off marks, they are determined by the admin only. You need to apply online or offline. For further details regarding admission refer:
http://www.loyolacollege.edu/admission/courses-offered.php
If you belong to Tamil Nadu HSC board, then the applications for B.Sc courses are closed from 25th May.
Other board students (other state) can apply 3 days after the results of their respective boards.