Hello. You are eligible for applying in JEE Mains 2019 with BBOSE passing certificate. But you also must fulfill all the other eligibility criterias required. 

For admission in NIT Silchar you have to clear the cutoff marks. Last year the max closing ranks in NIT Silchar for some of the branches were:

• 79941- civil engineering
• 29626- computer science
• 70847- Electrical engineering

You can check the link below to know more about the cutoffs for different branches.

https://www.careers360.com/university/national-institute-of-technology-silchar/cut-off

To know more about the eligibility criteria for JEE Mains 2019 check the link below.

https://www.google.com/amp/s/engineering.careers360.com/articles/jee-main-eligibility-criteria/amp

Hope this helps. For further queries feel free to comment down below.

Good luck!