Sunish,
You are correct. The PMP Exam eFlashCards are taken 100% from The PMBOK Guide. They are a tool that is intended at making your studies of the PMBOK Guide easier.
You asked: "Can it help me in clearing CAPM at first go?" - That is a difficult question because it sounds like you are looking for a guarantee, and I cannot give you a guarantee. If you study the PMBOK Guide 2-3 times, study the HeadFirst book and use the eFlashCards to test yourself, then you are on the right track. The cards will help. But they are only ONE part of your studies.
However, you should also answer as many CAPM sample exam questions as possible and maybe even consider spending some money and signing up for a CAPM exam simulator.