Hi Smriti,

Yes, you are definitely eligible for PCSJ exam. The eligibility criteria are as follows, please read it carefully. 

• Candidates must be an Indian citizen.
• They must have the domicile of their state to get a reservation and the relaxation benefits.
• They must have a degree in law from a recognized university/institute.
• The age of the candidates must be between 22 years and 35 years
• Candidates of the reserved category will get the reservation and relaxation
• The age relaxation for SC/ST category will be of 5 years.
• The age relaxation for the candidates of OBC category will be 3 years.

Only LLB is compulsory, Btech is irrelevant. You are eligible to go for it.

Good Luck!