In the experimental determination of surface tension the capillary rise for a tube of internal diameter 1 mm is 30 mm. If the cappliary tube is than slowly pushed down untill the top of the tube is 20 mm above the surface of liquid in the beaker, the true statement is :
when the exposed height is less than, 30 mm, the liquid rushes up resulting in an overflow
the angle of contact decreases untill the angle is obtuse, with no overflow
the angle of contact increases slightly with no overflow
the liquid surface in the tube remains hemispherical all the time with overflow