I am no authority on this particular matter but i must share my own experience.
Your smiling face gives a bad impression to the psychologist and according to psychologist it is sign of nervousness.

In interview, you must keep a face not so smiley not too straight, like you mean business.

The last part will not affect your performance but you should have refrained from argument with the chairman.

The longer the interview is the better chances you have of your selection.

Best of luck and these interviews are part of learning process. Your knowledge is already checked in your written test so, even if you do not know the answer, saying sorry to that question is a wise choice.

__________________
A moment of pain is worth a lifetime of glory.