Hi Aspirant

This is not so.Even if you have covered all NCERT and other books but still this may vary because of the difficulty level of the question paper changes slightly every year.There are 180 questions each carrying 4 marks and -1 will be deducted for all wrong answers.In order to check whether you are prepared or completed everything you can join mock test like Aakash institute mock test,Allen ,Resonance ,Bansal classes .These are reputed institutes which offers mock test before the exam.If you are scoring well in the mock tests you chances will be fair.

All the best.