Hi shweta dibbi, OCPJP(CX-310-065) is now OCPJP(1Z0-851) with same objectives. I think, As you are sitting for the exam on september,
you should sit for latest OCPJP7 exam.For OCPJP7, you need to give two exam,
Java SE 7 Programmer I and Java SE 7 Programmer II. look at the oracle site
Here.
Of course, you can give OCPJP(1Z0-851).