corporate intranet portal with drupal 7
I would like to know whether corporate portal can be built with
  drupal.


Yes it is possible.


  Please let me know if there any modules for the above requirement or
  any opensource for this.


The question cannot be answered properly without knowing the exact requirements and then digging very deep. The result would be mostly writing a book. 

To be honest as you are new to drupal and the way your question "sounds" to me" you are likely to fail with the project. Therefore I would recommend you check out how far open atrium (Drupal 6) or other install profiles / distributions meet your requirements and try to sell one of these (plus customization) to your client. Or at least first look how the authors of open atrium, Drupal Commons and others do things and then ask specific questions.