What is the pass mark of btech 1st semester wbut?

There's no single "pass mark" for all B.Tech 1st semester subjects in WBUT (now Maulana Abul Kalam Azad University of Technology, MAKAUT). The passing criteria usually involves obtaining a minimum number of credits rather than a specific percentage. The exact credit requirements and the grade point needed per subject to achieve those credits will be specified in the MAKAUT's regulations and your course curriculum. You should check the official MAKAUT website or your college's academic regulations for the precise passing criteria.