hi,

see if you want to improve your marks in physics and want to score better, then you should write physics, as per your score you need to study atleast more 50% syllabus of physics of 11th standard, however before writing improvement make sure you have good preparation or you can take better preparation this time. however in most of the board exams like west bengal state board, 11th score is not matter, 10+2 certificates is based on 12th score /final  board exams score.