Hi Bhaskar
Here is a question & answer given by Mr.Khanna related to your question.
My employment based I-485 is currently pending through employer A. Can I take a few months off and go work for employer B?
Theoretically –yes, but practically it may not be a good idea. A green card is based upon a job that is in the future. You must join it (unless you are taking advantage of 485 portability) upon receiving approval of the green card. What you do before approval of the green card should not be of concern to INS. As a practical matter, INS would question this arrangement where you are taking off for a few months from the sponsoring employer. INS could doubt that employer A may not longer have a job open for you.
hope this helps, suggestions / opinions from anyone welcome