[sudo-users] SUDO PERMISSIONS

[Sam Mabjish]

Hi to ALL,

I want to give an operator the ability to change passwords and unlock userids on my unix server. Is there a way in sudo to limit the excecution of passwd, and make it only change the password of a group of userids that I specify or define?
i.e. I don't want the operator to be able to change the passwords for all the users defined on the system. I want him only to be able to change the password for a group of users? 
If there is a way in sudo, could you please give me the syntax?

Thank you all in advance
sam