is there a parallel of task manager in Mac? what to do if an application does not respond

Force Quit.

Press command + option + esc keys together at the same time for about three seconds

Wait.

When Force Quit window appears, select application, if not already.

Press Force Quit button at the bottom of the window.

Wait. Application will quit.

More on this:

http://support.apple.com/kb/HT3411

Activity Monitor ( Task Manager)

Applications > Utilities > Activity Monitor