(i) False, because longer chord subtends larger angle at the center, where as shorter chord subtends smaller angle at the center.
(ii) False, because larger chords are closer from the center.
(iii) True, because equal chords are equidistant from the center.
(iv) True, because chords of congruent circles, subtend equal angle at the center.
(v) False, because a circle cannot be drawn though three collinear points.
(vi) True, because AB is a diameter.