Hello STudent,

According to to central government listing 3b category comes under OBC for all examinations including UPSC. You can go through the official website of national commission of backward class to have a better idea.

Union Public Service commission each year conducts examination for civil service recruitment in various government service like IAS IPS IFS and in some Central services. The examination date has been announced, the UPSC examination will be held on 18th August. Click on the link below to know more about UPSC

https://competition.careers360.com/exams/upsc-civil-services-exam