Hey Rishab.

Yes a student who had science stream in class 12th can appear for law entrance examinations after 12th. There is no restrictions on the basis of streams. The eligibility criteria differs for each entrance. The criteria for CLAT ( the most sought after entrance  to score a minimum aggregate of 45% atleast in your 12th or equivalent qualifying exam.

Other than CLAT a few entrance exams are- AILET, SLAT, LSAT, PU BA LLB, Christ University Law, MHCET etc.

Best of luck!