How many marks do I need to score in class 10th and 12th in order to get admission in a good engineering college for B.Tech in CSE?

In class 10th, you only need to get marks enough to get science stream and that depends from school to school and in class 12th, you need to get at least 90 % to get a good government engineering college and rest depends on JEE mains and advance.

Class 10th marks do not matter to get admission for B.Tech. You need 75% in 12th to get into NITs/IITs/CFTIs for B.Tech. For SFTI's you need 45% marks in PCM, for state government aided it differs.