Hello Bhanu

It is not a illogical question but yes CBSE has kept it since very long.

CBSE: The Central Board of Secondary Education (CBSE) has kept the bar at 33 per cent for class 10 and 12 students. A score of at least 33 per cent in their internals and practicals is required to pass the subject and at least 33 per cent in the board theory examination in order to clear the subject as a whole.

Source: ( CBSE )