Is there only a common CUCET test for getting addmission in these universities ? how can i dowload the previous years qn paer of MSc Botany ?

CUCET stands for Central University Common Entrance Test.  By clearing this test you can apply for Central University of -

1. Haryana
2. Jammu
3. Jharkhand
4. Karnataka
5. Kashmir
6. Kerala
7. Punjab
8. Rajasthan
9. South Bihar
10. Tamil Nadu

There are most probably no way to download previous year questions. But you can visit the cucet official website click on the following process:

Programs > See downward and you will find a drop list saying program level select category 2 pg > Click on university drop list and select the university > click on the program droplist and select the course .

By following the above process you can download a pdf of sample paper.

I hope my answer helps you. All the very best for your future endeavors!