Hello Alekhya,

You can not get BARC previous year paper because of BARC Consider BARC Recruitment paper as their Intellectual property.

The statement regarding this fact is quoted below,

"Question papers are the intellectual property of this centre , The disclosure of which will harm the competitive position of other  candidates."

If you want to study for BARC then go with the syllabus. Practice all concept and theories. You can consider GATE previous year papers.

All the best.

No. You can't find syllabus and previous year question paper, so don't waste your time in it. Just refer syllabus and previous year question paper of GATE exam of your stream. That would be quite sufficient. You can also check previous year question paper of isro exam.
All the best.