admin approval required for specific roles registered using profile2_regpath I am using profile2_regpath for registrations . 

I have 3 roles. Students, Centers and Organisations. Is it possible to activate the users which are registered for Student role without admin approval ? 

The users who registered for centers or organizations role must need admin approval.

Default "Account settings" in Drupal have the option to activate users without admin approval but I can not specify the roles there.

Any clue? or any other module which I should be using instead profile2_regpath
You may be able to use Rules to accomplish this. Create a new Rule that is triggered when a user account is created. Then add a condition that checks what the role of the user is. And finally, an action that activates the user account. I think that would work - although I'm not sure if those triggers/conditions/actions exist. They probably do. :-)