JC mocks are a very hard set of exams that you will be facing in the lead upto your actual JC exams. They should be treated as such and you must be well prepared for it. Study all the material and do not try to skip chapters (Maybe you have to considering you haven't finished the course). Practice as many exam questions as you can. Its okay to make a mistake in your mocks but you have to learn from it because you can't afford to make any of those mistakes in the actual JC exam.