First answer is you can apply for any government exam if you are 12 th pass but the eligibility criteria of every government exam is different so you have to go through every vacancy notification individually if your marks fall under the eligibility criteria defined by them you are eligible for the post.some government recruitment exam which has no fixed percentage you just need to pass qualifying exam like in SSC MTS is Xth, RRB NTPC is XIIth, SSC CHSL is XIIth, SSC CGL is Graduation, UPSC Civil Services only graduation needed.

Second is,To become a BPSC teacher in Bihar, you must have a graduation degree in the subject you want to teach. Apart from this, Bachelor of Education (B.Ed) is also mandatory. The candidate must have passed either CTET (Central Teacher Eligibility Test) or BTET (Bihar Teacher Eligibility Test).